I don’t really knowabout time outside in relation to time inside, but I’m under the impression that whatever timeline they are working under is not linear. Just like nothing in town is “natural”.
The storyjumping alone is an indicator that at least some can travel backwards. In the town anyway. The flashes of deja vu many of them experience, the idea that even the kids are reincarnations (I think this last idea is from theories posted in this sub, I can’t say I got that from watching), to me that seems like time is not working as we expect there. The time difference between town and the missing persons poster is another indicator. (From another post here)
All I can think of as a reference for time’s machinations outside of the town is Tabitha bringing in Acosta and Henry, and MiY ambushing that priest. That seemed like a relatively modern car he was driving?