I'm homing in on 20,000 words. I know historical novels run longer than your average novel, but I'm not sure how much longer. Fantasy, by average, runs longer as well. So I'm going for 100,000 words and we'll see how it goes. Almost 1/5th way there.
I'm writing this novel in a rather episodic manner. This week, I wrote a couple of scenes from Mike and Ashley's final destination in the 20s, and now I'm writing a scene that takes place during their journey back in time, in the 60s. I'll smooth them all out at some point in the future. I'm not sure if I'll use them all, but I'm trying to make sure they each are relevant to the plot. Even fun "fish out of water" scenes must advance the plot, somehow.
I also have to figure out the rules of time travel. I decided to rule out the possibility of two "copies" of a person in the same place at the same time. If someone goes back to their own past, they become the only copy, even if the person must vanish in one place and appear in another. This means that Mike and Ashley would have vanished for brief periods in their own past while their future selves were visiting that particular time. I'm not sure if this will have an impact on the book, because I really don't get into their own personal past very much. But it will be an interesting possibility.
I'm also wondering if it wouldn't be fun to have someone they meet in one timeframe come looking for them in another. For example, they save a black teenage boy from a beating in the early 60s. Wouldn't it be fun if they run into him in the 70s--before they ever get to the 60s because they're traveling backwards through time--and he knows them and just wanted to try to find them to convince himself that it wasn't all a dream. And of course, they wonder if he was crazy until they finally meet him in the 60s.
Fun? Oh yeah.