Extending A Time - feeling confused

[OMJ03]

DS is 4.5 months old and we are newer to EASY. He is currently asleep after 1 hour 40 minutes of wake time (3 days), and goes to be super early after having only a 30 minute nap around 330 and refusing to go back to sleep. He habitually wakes at the 30 minute mark for all naps.  I always leave him in his crib but it takes anywhere from 10 min-40 min for him to fall back to sleep and often requires shh-pat, PUPD, httj and at times a soother. I'm hoping that the 30 min waking will go away once we adjust his A time. Do I extend just the morning A time or do I extend all A times right away by 15 min? For the morning activity he seems so tired that even 1.40 seems long but I'm hoping that will change?

[Ima shel Alon]

Maybe he needs his first A time even shorter than 1:40h? My DS always needed his A time in the morning to be shorter than the rest of the day.
If you want you can try and offer only 1.5h in the morning and see if the nap extends after 4 days. If you still think he is UT and needs more A time then it's very much up to you if you want to start just with the first A time or tackle all of them at once.
IIWY I would increase just by 10min and not 15, because he is not far from what he "should" be doing and a 15min jump might be a bit too much for him.

Good luck!