I’ve done departures at 6 am when TSA hasn’t opened all the lines yet. The problem is, and I’ve run into this multiple times. Due to crew rest rules I’ve had planes delayed e en when some are listed as “ cancelled” but it still operates. Your airline has a delay it gets cascading effects into first or the morning hub flights.

I’ve gone in/ out mid afternoon and it can be nothing for wait times. It depends on the flight schedules and what’s scheduled to depart around the same time.