Yes, you should be fine scheduling it early and picking up later. Also, Hertz generally lets you change times on the same day without affecting the rate after booking as long as it doesn't change the total number of days.

Generally, there is no penalty for dropping a few hours early.

Just for completeness, you might also want to get a quote via the link below. Sometimes we can find non-prepay rates that are comparable, which is obviously preferable.