Nap transition help!

Hey guys I need some help with 3 to 2 nap transition. My son has been an okay napper for the most part, sleeping 1 to 2 hrs per nap on most days until he turned 9 months. He's also always been an early riser, always woke up earlier than 6.15.

Now, lately (for the past 2 weeks) he's been refusing at least one of his 3 naps a day, either that or that nap will only be about 30 minutes. I tried stretching his wake times slowly and did this for about two weeks now, but this week it became so bad that I moved his waketimes back to 2.30 minutes. But this works some days, but some days it doesn't.

How do I transition properly and what do I do when he refuses to take a nap because he's over or under tired. How long does it take for him to transition and how do I know a wake time even works, if one day he does fine, but another day he goes crazy.

Just a lot of questions, because I'm just a little confused about this 2 to 3 nap transition.