I'm not familiar with Scrivener to answer this question adequately, but I'll give it a shot. I have had situations like this in my outlines and timelines (which I do in a spreadsheet, naturally, lol) and it can be tedious to renumber everything, but I still think it's a worthwhile exercise to have a handle on your timeline early on so you don't create unrealistic scenarios, like having something happen in winter when it takes too many months to travel on foot, etc. It's tedious (and annoying!), but not a show-stopper, to have to renumber your hours/days/years/whatever on sixty scenes. You could probably do it in the fifteen minutes allotted for a Prep assignment, depending on how easy it is to edit in Scrivener.

But I'm interested in other comments, because we could have pushed back the first timeline draft another week.

Cheers,
Michelle