Considering I did all the night wakings and all feedings since I wasn't able to pump and DS3 refused a bottle, let alone formula, my DH was concerned about my sanity adding a 4th. The boys are 12y, 9y and 19 months and sometimes he comes home and I'm like ahhh you take them, I'm done today lol and the fact that I LOVE to sleep. (I do love saying "The Boys" rather than the kids but reallllly want a DD) he was talking about finances, ect but then said "Ok let's do it, I'll be working just as hard anyway"
Granted my youngest only slept through the night at 11 months old and is just now self soothing himself to sleep. So like others have said, let some time pass and let him "forget" the newborn stage and sleep deprivation. In the meantime do all u can to sway so when he says ok, you can start TTC and be swaying already.