I am renting a car on April 28 at the orlando airport at Hertz what is the earliest I can pick it up. My reservation says 8AM

Airport rentals have floating inventory so the timing shouldn’t matter; you can pick your car whenever you land at the airport. However, your reservation starts the moment you check out of the parking lot. Say, you pick up your car around 6 am instead of 8 am on April 28 and return the car around 8 am on April 30, you will be charged for 3 days. Hope this helps.

I went soon as I had no problems

Probably 5 AM if you are gold

They didn't have anyone to help there at night. I would double check if you can come earlier if you're appointment time doesn't specify it. They have security, but didn't see any attendants when returning car late.