Re: need to get 4mth old on a sleep schedule.
4 months is a hard time. I feel your pain.
I think it's too young to start serious sleep training routines. But at that age I started putting LO down and letting her fuss for a few minutes (like 2) to see if she could self soothe and go to sleep on her own. I did it only in the day time and I think it did work to train her to settle herself.
I seem to remember at 4 months, the LO was waking up at about 10 pm for night time hijinks as well.
Are you swaddling? It really helped my LO get back to sleep after eating.