Late bedtime help

Our little lady (4 months this week) sleeps through the night but we can’t get her to sleep earlier than 9:30pm. She’ll sleep until 8:00 or 8:30am though. Her naps are just 30mins or an hour if we’re lucky during the day.

Reading books seems to get her really feisty and excited. We bathe every 3 nights and she’ll be easier to get to sleep then. I’d like to get her to sleep an hour earlier especially because I’m starting work again soon. Any advice mommas?