How long do you apply pressure to a wound to stop bleeding?

That all depends on the person and the depth of the cut, where the cut is etc...

If it is severe, on a vein, bleeding profusely, go to the doctor or call 911 immediately.

If it's a little cut that is just pestering, try pouring white sugar on it. The sugar does NOT burn at all, you won't feel it. The sugar will help to clot the cut. It will soak up the blood and create a makeshift scab until the blood will clot on it's own. Don't peel it off, wash it clean with warm water and antibacterial soap after at least an hour.