Hang in there PeepersMom! Don't beat yourself up -- we just try to make our best guess during these transition times and when it works we think we are doing so well, and visa versa when it doesn't. I think sometimes they're just messing with us to get us ready for all the second-guessing in years to come!
It's a delicate balance of looking at clock time, awake time, and signs, and not one that I've mastered at all, but if PJ isn't overtired from the last couple nights, maybe you can see how long he will go today? When he's been well-slept, our LO sometimes surprises us with how long he can go from an early nap until bedtime. (And, of course, when he sleeps well that night we congratulate ourselves on how smart we are, and then if we wakes early, we curse ourselves for making him overtired!
)
Our LO has been alternating the past week with early wake up/2 nap day/later bedtime and "later" wake up/1 nap/regular bedtime. It makes me nervous to go back and forth, but I'm trying to make sure he's not overtired first, and then maybe we'll go back to stretching him a little more again. Ugh!