It looks like you've had some success with extending that first A time - how long was the next nap?
If his first nap is short and you can't extend him, then the next A times should be shortened, because he's now OT (count the time you unsuccessfully try to get him back to sleep as part of his next A time). With my dd - I'd try extending A time, if that lengthened her naps, GREAT! If not, then the A times the rest of the day were shortened (I'd try to get her back to sleep, and if not, then up, feed, diaper change - then right back to sleep to try to beat the OT cycle) Does that make sense?
It's a combination of figuring out A times...but keep in mind that if the first nap is short, your lo is now OT and you have to try to beat that the rest of the day.