To the best of my knowledge, if someone skips their subs in the morning they can get the full effect of using the same day. Withdrawals aren't really a huge issue until there is physical dependency. I don't think you need to worry about how you'll know he's using; you'll know. If he wants to use then he will use, you worrying or stressing over it is just focusing on the future instead of the here and now. One day at a time. what are your boundaries?
What are you doing for you? Instead of focusing on his recovery, which he needs to own, what about working extra hard on your own recovery?
