All my kids were combination fed at some point (DD's 1 &2 at 3-6 weeks old, DD3 at 5 months). We did the bedtime feed first mainly so DH could do it, it did not help them with sttn (well DD1 did sttn early on but she is a pretty textbook sleeper so may have anyways). If he has had issues with formula I might try it first thing in the morning just in case. What formula did you try before? DD3 did best on Goodstart, she has issues with dairy but it was okay (dairy based but only whey and broken down).