Baby wake up times

Has anyone had any luck getting their babies to sleep a little later? I have a 4.5 month old and in the past month we’ve gone from starting the day 730-830am to closer to 6. Then first nap of the day may start as early as 730. Prior to this, she would often wake up around 6, coo quietly for a little while, and then go back to sleep on her own. Is it possible to get back to this?. We try for bedtime at 9pm and wakes up 1-3 times at night for feeds.