A bloody nose should be able to be stopped within 15 to 20 minutes.
If you can't get the nosebleed to stop within 20 minutes you might need to go to the emergency room to get it stopped.
Normally you can get a nosebleed to stop on your own at home by pinching your nostrils together for up to 15 minutes and while doing so lean forward.
Don't lean back when you have a bloody nose as it can drain blood down the back of your throat which you do not want.
Always lean forward when you have a bloody nose to stop it.