Just cracked open so the ball barely moves/floats.
Set nitrogen regulator to 50(or less if flow meter's rating is lower), then start out with full flow for a second or 2. Then close regulator, and shut flow valve. Open reg, and then adjust flow valve to barely float ball.
If your actually gonna braze the schrader whee your putting nitrogen in first, and then go inside and braze those joints, then come back out and finish the opposite line, no need to go full flow first.