P.G.
Transition to a twin size mattress on the floor. Daddy can snuggle with him as he falls asleep. If daddy falls asleep, no big deal. Then daddy can transition to sitting next to the bed as DS falls asleep, then to a chair with his computer as DS falls asleep, etc. It's more gradual, gives daddy the time with DS, is more comfortable for everyone, and if DS wakes in the middle of the night (he will, his brain is changing a LOT and he can't help it), hubby can take him back to the bed and snuggle again if needed. It worked for us.
EDIT: Another mom had given the suggestion re. sitting in a chair with my computer, because I was a snuggler and it took forever for my son to fall asleep. We both do prefer to have the time together, so NOW I snuggle for maybe 5 minutes, then go to the chair if my son is still awake. He falls asleep VERY quickly once I'm in the chair, where it would take much longer for him to fall asleep if I were snuggling with him and he didn't fall asleep right away.