The three witches bring the kingdom several years (I believe it's 15, so Tomjon will be 18 years old upon his return) into the future. How does this jive with the other books around it? Everyone brings up the Small Gods problem of the ending being a hundred years after the beginning, but I don't recall anyone trying to explain the fifteen-year time gap which should logically fall between Sourcery and Pyramids (or, since there's some debate over when Pyramids falls in the timeline, Sourcery and Guards! Guards!). Certainly, this makes Wuffles being 16 in The Truth all the more confusing.
Time Monks. Seriously, Time Monks is the explanation for any temporal shenanigans affecting or not affecting anything and going unnoticed.
What does Lord Vetinari's dog have to do with Lancre?? But anyway, as the previous poster explained, Thief of Time explicitely states that the Time Monks move time around, and have been moving a lot of time from the deep sea and high mountains into Ankh-Morpork to allow all those inventors enough time to speed up development, but and this is important, without actually making all the people in the city age faster. Societal and technological progress simply moves faster in the cities than in the countryside.
Wuffles was introduced as a very old dog in (I think) Sourcery. If fifteen years passed between Sourcery and Guards! Guards! (and by proxy, the rest of the timeline) then he would be much older than sixteen. The fact that he isn't would seem to imply temporal nonsense, but the History Monks do clean that up a bit.
It could be that Vetinari's first terrier passed away immediately after Sourcery's events, and he got Wuffles # 2 as a replacement. The guy owns dozens of sets of identical clothing, so he won't have to be bothered with deciding what to wear; naming his new dog after his previous one would be consistent with this.
Wuffles is 16 at the time of The Truth, which chronologically takes place about 16 years after Sourcery. This troper's theory is that Coin turned him back into a puppy at the end of that novel, to make amends for Vetinari being deposed and turned into a lizard.
Given how little interplay there'd been between Lancre and other regions prior to Witches Abroad, it's possible that Wyrd Sisters actually begins before The Colour Of Magic does, and only comes into synch with the other books after the time-skip. If that's so, it might resolve why we haven't run into Esk again: she'd have graduated from UU quite a while ago, and left the city.
Granny knows Rosie Palms, who doesn't seem to have aged a decade and a half between Equal Rites and Maskerade. Moreover, Archchancellor Ridcully is also from Lancre and also knows Granny Weatherwax. So either Ridcully was living in Lancre when Granny sent it through time (which would put him out of sync with the wizards at Unseen University), or he was living somewhere else, presumably somewhere in the Sto Plains or Copperhead Mountains (which would put him out of sync with Granny). Since neither is the case, we should just assume that the History Monks did it.
Rosie Palms didn't actually appear in Maskerade. There was a young woman who recognized Granny at Ms. Palms' establishment, but that was a different seamstress (Colette), who could have met Equal Rites' Granny as a child. Granny even mentions that Ms. Palms is thinking about retirement.
Ridcully was living elsewhere up until he was made Archchancellor. That's part of why he was made Archchancellor, actually, since he wasn't around for the embarrassing events of Sourcery.
Rosie Palms was already a Seamstress (hem hem) in Night Watch, so she's been a part of the Guild (if not yet a madam) long enough to have met Granny back then. Carrot in Guards! Guards! assumed Mrs. Palms was the mother of Reet and the other prostitutes, implying she looked old enough to have grown-up daughters.
Mrs. Palm was also one of the "most senior guildmasters" who confront Vimes in his office in Feet Of Clay. Even if this only means she's one of the longest-incumbent among the city's guildmasters, it still supports the idea that she's middle-aged herself.
Granny is secretive about her own powers, and probably wouldn't want to share information about witchcraft with a wizard - not even Ridcully. If his family's estate lay beyond Lancre's border (so he missed being caught up in the time-shift), and he'd said something like "So it's been what, sixty years?", she's hardly going to go out of her way to explain that, for her, it's only been forty-five.
Ridcully didn't grow up in Lancre, he only went there for his summer holidays as a young man. His family estate is elsewhere in the Ramtops.
Is there any reason why some (or even all) of the stories between Wyrd Sisters and Witches Abroad couldn't have taken place during that fifteen-year gap? We know the books can overlap: the opening scenes of Night Watch run concurrently with the climax of Thief of Time. This might just be an extreme case.
The Discworld Timeline makes it fit by putting Sourcery and Pyramids in the gap (and unspecified "events from Equal Rites", but that has to be a mistake). It also places "Troll Bridge" then to explain discrepencies in Cohen's age. Guards! Guards! can't happen while Lancre is outside time, though, because Carrot's father talks to Magrat at the start.
Technically Magrat didn't appear in Guards! Guards!: it's just mentioned that a messenger was sent to ask her a question. It isn't explicitly stated that she answered it, so Carrot's aunt might have made it as far as the border of Lancre, found everyone frozen in time (see below), and come back unsatisfied.
What would happen if, during the 15 year gap in time, someone decided to enter Lancre? Like say someone leaves Lancre right before the spell is cast and comes back a year later? Would they be brought 14 years into the future by the spell during the time gap?
If it's anything like the fairy-tale story which gave the witches the idea, they'd find everyone frozen in place, waiting to wake up. A similar situation was encountered in Witches Abroad, where Lilith had put a palace into suspended animation, although that time Granny's party was able to break the spell ahead of schedule.
Or they would have simply encountered empty fields, and spread rumors about a mystical and idyllic kingdom that only appeared once every fifteen years. It would be the perfect place for a Brigadoon joke, but Pterry didn't go in that direction.
What happened to Tomjon's mother the Queen? Surely she didn't die in childbirth, not with Nanny Ogg in attendance.
Doesn't mean she couldn't have died some time afterwards. Or fled into exile when her husband was murdered, separately from her child to make it easier for both of them to disappear.
If she'd fled into exile immediately after the murder it probably would have been mentioned, so I'd say she probably died.
It's only on approximately my 40th rereading of the book I've notice that zero mention is made of the Queen, and how odd that is - and considering how young an infant Tom Jon is at the beginning, childbirth seems the most obvious culprit for her death. She can't have had much chance to meet with accident SINCE then, after all. However good both Granny and Nanny are at midwifery, even they can't have 0% mortality - but what's odd, if one of the witches did attend the birth, is that they wouldn't mention it over the course of the story. And that when the populace begin to turn against the witches, a 'failure' in the Queen's labour isn't brought up. Still, maybe the Queen had an external doctor attend the birth or something and the witches weren't involved .It's also strange that Verence I doesn't wonder if he'll encounter his wife's ghost if she is recently deceased, though.
Near the end of the book, Nanny Ogg says that she attended Tomjon's birth, and also calls her the late queen. So I'd go with 'died in between son's birth and husband's death' too, although a Deathbed Confession of who Tomjon's father might really be is also possible.