We do have a window. I put him in his swing for a few minutes so he can just be alone to calm down, suck on his hands, etc. Then I go get his swaddle, I pick him up, tell him it's naptime, then swaddle and give paci, walk to nursery, turn off lights, close blinds, and sing one lullaby while patting. Then I start shushing. He likes being cradle held not over shoulder, I usually nestle his face in my arm so he can't look around. He falls asleep almost instantly arms. If I were to hold him for the whole nap, he would sleep indefinitely. If I do this without a dummy, he fusses and it takes me about 15 min to put him to sleep (again on my arms) but again he will sleep forever as long as I hold him. He will wake up during jolts in my arms and fuss for dimmy but if I hold him super tight and shush louder he will calm down.
Now I've attempted to put him down during deep sleep, he will only make it through one sleep cycle, with or without dummy. I'll try to stay in room next time for whole nap to hold him down and see if I can help him through. I did run in once when I saw him wake up at a 60min nap last night, he sort of tried to stretch in his swaddle, spat out dimmy, but his eyes were open and when I came in he just smiled.
If I shush pat while drowsy but awake if he doesn't have the paci he just stares and smiles and coos and won't stop making me laugh and if I shield his eyes he gets mad. If I do with with paci, I need to shield his eyes, he will fall asleep that way. But then the paci becomes and issue because if it falls out during the process of light sleep he wakes. So I have to shield and hold it in and pat him. It's quite the acrobatics!