I believe it may be anywhere in the ball park between 20-30 minutes. Basically you wanna slowly continue adding water until it kinda gets a sweet spot between pasty and dry. So you raggarh, add a little water, raggarh and so on. I can double check, but I think they read any type of bir ras bani.
Some people opt to put all the ingredients in at one time and others (like the video above) add it as they go along.