We will be staying in Nafplio at the end of our 2 weeks on mainland Greece. We will have a rental car, and will need to drive back to Athens airport to turn in our rental car and catch a 12:30 pm Aegean Air flight to Crete.
We are very much early morning people, so we're thinking of leaving Chania about 6:30 am, which should get us to the airport no later than 9 am. We would need to turn in our car (thru Athens Car Rental) then checking in for our flight to Chania. I've checked sunrise-it 6:45 that day, so we wouldn't be driving in the dark for any length of time.
Our tickets will be refundable and changeable, so we could always catch the next flight, I think around 3:30, as a back up plan.
Is this realistic, or are we cutting it too close? On the other hand, I really don't want to give up our last night in Nafplio either!
(If this was our flight back to the US, I wouldn't even THINK of taking a chance!)
I think it sounds FINE. 3.5 hours is ample time.
Since your airfare is flexible I'd take the chance.
According to this website, https://www.rome2rio.com/ drive is around 2 hours. Google Maps also should give a very good estimation of the driving time based on the time of the day.
If you have wheels rolling as planned, you should have no problem.
If sunrise is 645, there should be some 'pre-dawn grey', so unlikely you will be driving in night time black at all.