The main thing Tracy said was to listen to your baby, that this is not a schedule but a routine - activities logically follow each other, there is a general timing to it but in the end, your baby is not a robot, he won't always sleep and wake on the hour.
Its quite possible the move to 4hr EASY will wok but if he's nearly 5 months, his ideal A time could be more like 2:15-2:30, average A times at 6 months are 2:45-3hr so you may have to increase further than you'd planned.
As your days become more age-appropriate, your nights should get better.