Sleep training

Hi moms, my baby is 5 months old. We've never made schedule for him cause since he was born we've been following his cue. After the newborn phase, he sleeps at 5-530pm and since we've been consistent he naturally will sleep at 5-530pm all the way till 2-3am (to poop). He automatically signals for milk at 9pm or 11pm, then sleep instantly after milk. But He wakes up at 2-3am automatic to poop (most of the time) and then he'll be awake for 1-2 hr. And then sleep, and wake up for milk 4 or 5 hours later. He can sleep on his own wirh pacifier. I don't bf; he's on formula. Nap 30mins -1.5hrs Wake window 2-3hrs Any of you experience the same thing? How do i change his bedtime to 8pm and make himsleep overnight? Also he always wake up after poop.