Hi Jen,
I agree with Katherine, little boys do tend to take longer to potty train. Andrew was diagnosed T1 at 7yrs old, i first had him potty trained at 3 during the day and 3 and half at night, then he went through a wet the bed stage from 4-8yrs(this could have been due to slowly developing diabetes!), after diagnosis we retrained his brain via an alarm system tied to his PJ's.Strangely Andrew had an aversion to poo, he pooed in a potty but would pee in his nappy happily,and if he did do it in his nappy, he often tottered towards me nappy off, poo rolling around in it :lol:
Every little boy is different, and Khaleb will be the same, i don't think his downs syndrome will hold him back, i would have a go at leaving his nappy off with potty ready during the summer months and see how it goes and leave nappy on during nights. If no luck during this summer theres always next summer, and there really is no hurry,
Take care Jen, hugs for Khaleb
Suzi x