At LEAST four to get the full benefits of it. Once in the morning before you get up, another last thing at night before you sleep, and then two more at other times during the day.
If you can’t manage a strong edge for some or all of those, don’t worry about it, just masturbating without cumming is more than enough to keep you horny and in a state of denial.
In fact in general you’re better off not doing too hard an edge in case you slip over, which you want to try to avoid, of course. Better safe than sorry when you’re starting out.