We do 4 hours but last half hour can be a push.
3.5-4hrs for last window, I usually go up with him for the last half hour to give him his bottle and have a cuddle xx
I do 3.5 hours - wakes up from 2nd nap 4pm bed by 7:30. Usually wakes up 6:45-7am. Can’t stretch him longer than this atm or else he gets overtired but every baby is different!
Put him to bed earlier if he's knackered? My little boy wakes at 4 and goes to bed around 7/7:30