It varies a bit animal to animal. But starting them in F/T young is your best bet. You may offer and get lucky and your new BP will take it first try. Others are a bit trickier, but I wouldn't stress over that yet.
My two cents: be ready for whatever, but hope for the best. Don't stress yourself out over something that isn't even happening yet.
If you try and get refusals, we'll be happy to help you out.