The routine looks good, but I would try to push the first A time out closer to 3.5 hrs if you can. Yu may need to cap the pm nap at 30 mins after a solid am nap so he is tired enough for a good nights sleep.
14 mths is a developmental leap too, so could definitely be a bit of SA. Given he has been an independent sleeper before, if he is well you can do Wi/wo, or otherwise GW....with GW your first step is to have him fall asleep in the cot, even with your hand on him. But not in your arms.
What do you think?