Not 100% on length, I think I did gradual withdrawal of mins if you get what I mean to see what suited DS. For example, I cut back 15 mins off 2 hrs and saw how he did, and then if there was no change, half an hour. I think you can tell what works, too much off = grumpy rest of the day. What time does he go sleep. I found if I put Jack down later than 11:30am, he would not sleep at 7 as was not tired enough IYKWIM