i would be careful about going in before he is really crying "mommy i need you", they can quickly learn that mommy comes when i do this. if he's just annoyed or shouting or mantra crying don't go in. sometimes they also do a start stop cry, so i always count to 10 when she's crying (or go to the bathroom) before going in
here's a link for you:
https://babywhispererforums.com/index.php?topic=95670.0he may be gearing up to go to 1 nap, but you want to delay it as long as possible (usually between 12 and 18 months, but the closer to 18 months the better!)
sounds like yesterday was better, great no NWs. this is always my gage - if i don't get NW then i'm happy!
is he still taking a good amount at all 4 bottles? you want to go to 3 at some point (we're already on 3 for the last 2 weeks and DD is almost 9 months)
HTH!