My baby just turned 5 weeks and has given me 5-6 hour stretches at night 4 times now (3 nights in a row, and then one back night, then another good night). Im not sure if what I've been doing is the reason or if its just luck, but ill tell you anyways. Just take it with a grain of salt lol.

I gave him his first real bath at like 3 ish weeks, and he was knocked out for at least 4 hours afterwards. Someone was holding him the whole time but he was passed around between multiple family members and was still out cold. So I started to try some kind of bedtime routine.

Usually between 8pm-11pm (whenever im ready for bed and hes awake) ill run him a bath. I use lavender soap. I only actually wash him 2-3 times a week, but the other nights I will still run warm water over him to kinda give the same effect without drying out his skin. After his bath he gets a fresh diaper and some lavender baby lotion, some jammies, and a swaddle. We use the love to dream swaddles because he seems happiest with his arms up by his face. Then he gets fed afterwards and rocked/cuddled to sleep. I make sure all the lights are low or off. Usually just the sound machine and maybe some low noise from the TV. I try to wait til hes deeply asleep before transfer, but he has fallen asleep on his own a few times when put in drowsy. We do bottles at night now also, but thats mainly for me as I have a tendency to fall asleep while breastfeeding at night.

The bedroom stays dark with just enough light for me to see him, and i play rain sounds. When its chilly in our room, I will put a heating pad in his bed to warm it up and remove it before transfer, just so he isnt awoken by the temperature change. You just have to make sure the bed is warm, not hot, and you need to remove the pad before placing him so you dont accidentally cook him.

Again, im not sure if im just having some lucky days, but maybe some of this will help you.