A pump time varies by a person and the time accustomed to PE.
I think with air pumping (I've done more
hydropumping), the usual time is 10-30 minutes, but I would suggest creating variation in the vacuum if you go over 10 minutes.
In my opinion you can utilize the 5x5x3 from
hydropumping into air pumping. Considering I enjoy
hydropumping so much, I suggest getting a water trap so you can pump with water. Of course that's somewhat more messy, but if you have the space and time, I highly recommend it.
So, vary the vacuum force, remember to do Slow Squash Jelqs and don't forget the principles of
SRT.
Have fun!