Yeah, timing is a huge part of it. Which can be torture if you don't have much patience... In the meantime just keep expressing your feelings in a casual, non-threatening way. Get creative... Ask them if there's anything you can do right now. Tell them you love/like them a lot (depending what your relationship is), but don't expect an answer. Or continue other things you've always done to show them affection - use your nickname/pet name for them, carry on an old inside joke or whatever. With my husband, I know he's always up for a hug or that I can randomly walk up and plant a big kiss in his face. With someone who's been traumatized more recently or is physically skittish, it should be something less "invasive," of course.
Other than that, just be there but do your own thing, i.e. take care of yourself and try not to count the days and weeks. ;-) And as Amethist said, be open if/when they're ready to talk. That, too, will come and go. If I was in the situation, I think I'd want to know there was someone who is on my side but who doesn't get completely swept up in it all.