My baby’s schedule got messed up...

My 4 month old was on a schedule...he would sleep between 9-9:30pm. Since Christmas because we were out a lot, it got messed up and he has been going to bed for the night at 1am!!!!

What can I do to fix this 😭

I tried a bath today and tried to get him sleeping by 9:30pm. It worked. But then he woke up 15 minutes after and will not go back to bed.