Cath thanks for your reply!
WU is around 7 am, on NNDs BT is 8 pm and he falls asleep pretty quickly.
He only naps at home in the car, and if he falls asleep in the car then I cap his car naps to 30 min and move BT back by 30 min.
I would LOVE to ditch the nap completely and I think he's ready however he attends preschool where the children are required to lay down on cots in a darkened room for at least 30 min, and of course he falls asleep every time. He only attends 2 days/week over the summer, but next week I'll be going back to work and he'll be there 5 days/week. I've asked them to start waking him after 30 min (they are going to try it today for the first time) so we'll see how that goes.
I'm not sure how long he naps on preschool days (I think it's at least an hour) - on those days BT is 9 and DS doesn't fall asleep until 9:45-10 pm. And wakes up at the same time, so has a short night, is tired the next day, and needs a nap.
I feel like we can't get out of this cycle of short nights then naps to make up for the lost sleep. I'm really worried he won't ditch the nap at preschool on his own, and that his falling asleep at night will just get later and later!