D.K.
It varies for every child. TO be honest there is no such thing as night time training. It is about how their body has developed. You can help it along by no fluids within a few hours of bedtime, no drinks in their rooms and make sure they pee right before bed, otherwise you have to wait until they wake up dry. ALl children are different. My son was potty trained completely at 3 and it took a while longer for him to start waking up dry. When he went five days waking dry I removed the pullups and did underwear. We had only one accident at night. Now he is aware enough to wake up and go pee and go back to bed if he has to go but can go 11 hours without having to.
I don't alllow drinks other then when brushing after dinner though and he goes before we read bedtime stories then tries one more time after and he seems to do well with that.
Tell your husband there isn't anything you can do about it but give it time. Kids have no control when they are sleeping, especially if they are sound sleepers. When their bladder is ready they will be. They are young still, so give it time! Most boys don't even get it 100% until 3 1/2 is the average for day time training too so you are ahead of the game.