Baby's sleep schedule is messed up

ฅ(• ɪ •)ฅ • 🦄

I need tips on how to get a baby's sleep schedule back on track. My little butt face is 6 months old and will NOT go to sleep till 4 am. He was doing very well. He'd go to bed at 8:00-8:30 then we'd get up at 6:30-7:00 then I'd feed him, he took a nap at 9:00-9:30 for maybe 30 mins to an hour then maybe another at 3 before bed. Ughhhhh I can't stay up another night till 4 am again -.-

Here's some cute photos lolz