I would start the wind down 20-30min BEFORE sleep time. If he can only handle 1hr of awake time then it will be 20-30min for feed, 5min diaper change, and then straight to wind down.
Keep an eye on his sleep window.. literally for some babies, this magical window is very brief. Once you see the first sleepy cue, do the 4 s wind down routine immediately. Also, keep his awake time at a minimal, and beware of overstimulation.
The crying is normal, YOU try and relax...that will help some. Does he use a paci? If not, that may help also.
Hang in there, sounds like you are on the right track - he will adjust soon. Although my LO still cries before nap time, it is just their way of letting off steam - so don't let it worry you too much.