Ivan going diaperless at night - 4.5 yrs old

Ivan is toilet train when he is awake, all thanks to his child care centre.
I have started to train Ivan sleep without pull up at night.

It was diaster the first 3 night, i try to wake him up in the middle of the night but not sucessful hence he pee in his sleep.
But on the 4th day onwards, I did not have to wake him up and he is able to sleep through the night.
There were a few occasions where he did a small pee and just wet his underwear, he woke up and shout for me to change his underwear and did continue his pee in the container(I put those takeaway container in the room) and he went back to sleep after that.

The only pending thing is, he still have to do his poo poo in pull up, signz, he need to squat while doing his big business hence he cannot use the toilet bowl.
This will be my next mission!