Oldest age for 2 naps per day?

[sste]

Our son is 19 months and has really enjoyed his 2 naps a day. I am not sure if this is due to our just returning from London 5 days ago or transitioning issues but he has started crying more before the morning nap and also waking up extremely early in the morning.

I always felt like more daytime sleep is great for learning, mood, etc. but is it time to switch him to one nap?

Also, at one nap is he likely to go to bed a bit earlier (he goes to bed at 830pm and wakes up at 6am with his two naps)? We would prefer 8pm and sleeping later until 630/7am.

[justincase]

I am of the "follow the DC's lead when at all possible" school of thought on this. My DS took 2 naps until 16 months and I *know* he would have kept it up even longer except that September came that year, I went back to work, and he had to go back to daycare and sort of adjust to what worked for being there. (He also took 3 naps until just shy of his 1st bday... he's just a nappin' kid!) It sounds like maybe your DS is telling you he is ready to transition. Nothing's carved in stone; you can always switch back if it isn't working for you/him.