This can be a tricky age, well the whole first year can be that way, but anyway, these LOs can be hard to read at this age and many Mamas have found themselves watching the clock more than the LO. The tires signs, in so many, can actually be "I'm bored, I'm thirsty, I need a change of scene" and so on. I would push an A closer to 3.5 hours if I were you.
The blessed micro car naps were tough for my DD, even after those she would need another 2 hours before trying for a nap and we would sometimes AP to avoid all the late PM OT chaos and screaming.
New skills can really mess things up. I would give LO time in the crib during A time to practice all this new stuff and make it playtime and then when he is in for a nap, let him be if he is not crying. I would not lie him down, if he DOES get upset, I would sit by him and pat the mattress and repeat your sleepy phrase.
HTH and keep us posted!