I’m having this same issue in AE CC 2018 and haven’t been able to find a solution online. I have a bunch of video walls with placeholders, in some shots there are 100+ placeholders, and when I replace them with the source footage I need that source footage to start at a specific time.
My current workaround is to set the in-point in the source, drag the source into a new comp, then option/replace the placeholder with that new comp. But if anyone knows a better way to convince After Effects that I’m really serious about my in points, that would be great/save a lot of time. And my project wouldn’t have 1000 unnecessary comps in it. Thanks!!!