How long is a good amount of time for a layover in Dubai?

Hi all,

I’m traveling beyond Dubai but all the options have layovers where the flight lands in Dubai at 7:40 pm.

I have an option of leaving the next day at 8:15 am, 3:20 pm, or 7:30 pm.

I was wondering if I wanted to see the Burj Khalifa, Dubai mall, and anything else to get a good sense of Dubai what time would be best to leave in terms of getting a good amount of layover experience?

I will also be visiting July 1st so not sure if a lot of activities are too hot.