New Year's Eve...maybe I'll still be awake at midnight

I tried a new swaddling technique last night. Instead of the Miracle Blanket, I used a Halo SleepSack, which we inherited from a friend. It was fleece, which probably was a little warm for Brendan since he had footed jammies on, and it was the newborn size, which was short enough in length that his feet pressed against the bottom of the sack. He definitely wasn't happy when I put him in it, and he woke up crying at 2:15 (usually he wakes up gradually with a lot of squirming and squeaking, which I hear over the monitor). Usually I catch him before he actually starts crying, to prevent him from waking my husband. Not this time; he was pretty unhappy. However, after he went back to sleep following that feeding, he slept until almost 8:30. Five whole hours. He did start squirming at about 7:30, and I did hear him. But I left him alone to see if he'd go back to sleep. He did, which is great (although I lay there for the hour, listening for any sounds that I needed to respond to). I know I need to let him self-soothe, but it's hard. I need to start small, like I did this morning. Maybe eventually he'll sleep through the night...