Hi
Welcome to the forum!
The correct brushing technique usually takes 2 minutes. In most cases this suffices. However in presence of gingivitis you need to be extra cautious. You must also brush the gums holding the brush (use a soft one) at a slight angle to the gums (around a 45 degree angle) and using short, gentle strokes. Tongue should be cleaned with the tongue cleaner. You must ensure that all teeth have been cleaned on the inside, outside using circular strokes.
The actual time spent does not matter. It is the approximate time most would require to correctly follow all procedures. Hope this helps. Take care!