Actually, what I do is open the windows slightly and turn on the A/C. That will cool the interior the fastest as the A/C is pushing the hot air out through the open window. From what I noticed, opening the windows on a hot day doesn't do much to cool the interior down, especially if the car is not moving.I respectfully disagree with that statement.
Without remote windows or remote start, experts (reader: you decide if you want to accept them as such) have commented for years that to get a hot car cooled the fastest, drive with the windows rolled down for a few minutes, then roll the windows back up and turn on the AC if you didn't already. Why? Gets the most heat out of the car the fastest and lets the AC concentrate on reducing the temp from, let's say, 110 instead of a much higher temperature.
If I sit in the car with the windows opened, it gets quite hot in there.
Opening the windows may help if it's relatively cool outside and the car got warm from sitting in the sun.