There are a lot of factors that will eat up available battery current. Aircraft weight (total), your throttle management, binds (if any) in the servo controls, and so on. It's tough to just pick a number from a specific battery/esc/motor combination without knowing more about what is going on and how you fly the plane.

For instance, when I started out with electrics, I was expecting 10 to 12 minutes of flying time, but got only three or four. I wondered why until I learned a bit about throttle management. That number increased to about 9, so far, with that particular plane, motor/esc/battery, and servo setup. Yours will differ from someone that has the same setup as you do. Best thing to do is just fly it and learn how to fly with minimum battery use (throttle management).

DS.