hi there,
definately continue with PUPD at his age.
he should be eating every 4hrs or so, so you should be on more of a 4hr easy.
I would think attempt first nap at about 2hrs of A time
now if that nap is short, you will have to use pupd to get him back to sleep, or until it is time to eat. if he does not go back to sleep within that period, then you may feed, have a quick diaper change and then attempt nap again.
so in this way, you have to flex the EASY a bit to try and fit more naps in. of course this is not ideal but it will get better as he gets used to new way of sleeping and gets used to more sleep in general.
so lets say, he only sleeps 20min----you may try 45min of pupd, if he goes back to sleep for 45min then feed when he wakes, if he doesn't go back to sleep after 45min of trying, then take a break, feed him, light activity and diaper change for maybe 30min and then attempt nap again.
HTH