I would expect to see a later first nap for a little of this age, so I do think you're right to move it later. We would normally suggest moving later by 15 mins at a time and holding for 3 days before stretching the A time again if needed. I'm not sure if you did this the first time and if not, you may need to hold the new time for a week or more before he gets used to it. It is hard for Los to adjust when they've been used to sleeping at one time, even though they need an increase in Atime, they'll still show tired signs at the old nap time. Persevere though, this is a case of mummy knows best.
Have you seen this average A time thread:
Average A times- BOOKMARK ME! So many LOs of your DS's age are managing between 3&4 hours A time between naps. I would suggest that you see if you need to adjust naps a bit further until he's going to sleep fairly easily and without lots of time playing in his cot first.
As for bedtime, you may need to move BT later, some Los need a longer day for a while before they begin to cut down one nap a little shorter. I would see how tired your boy seems at his normal Bt, if you think he needs more, push Bt back a bit.