F! won't be showing nor will the fireworks. WoC and the parades will run. That's the slow day schedule.
You have the right idea. Since the park has short hours, don't waste time eating. Have breakfast and dinner outside the gates.
I would aim to arrive at 9:10. Go through security which may take 5-10 minutes and get in line at the gates and wait another 10 minutes. The gaits on both DCA and DL can open up to 30 minutes early for Rope Drop.
On your quiet day they may not open 30 minutes early, there if no firm time, it mostly depends on crowds. But when they do they allow you to go up to the end of Main Street. It's a good time to either wait it out, grab a snack or wander the shops along the street.