Aug : Ai Sit himself UP

Last night we took Ai to dine out with P'pong friend's friends. But the party got late and passed Ai nap time. He was super cranky. I have to leave in the middle of the party take Ai home. It already ruined his sleep schedule, he slept for 1.30 hr. then wake up playing the sitting up game until 3 am.
He did sit up by himself couple times a week ago, but I didn't encourage him to practice it.
Now he keep practicing it; lie down on his back-roll over on his tummy-lift his tummy up by pushing with 2 hand and his knee-bend his leg to V shape-then he now sit up straight and give me a grin. Ai keep doing this over and over, PP said he practice it, so he remember how to do it. I think from now, he do it like a pro.