There seem to be two general schools of thought. One is to use a very sharp needle, 1.5 mm or 2 mm, and only roll once a week or every two weeks. You will actually skip minoxidil the day of the rolling and the day after. There other is to roll with a short needle, .25 mm, everyday before minoxidil. You can combine the two, rolling every day with .25 to increase absorption and then taking a day off of minoxidil and the .25 needle to wound with a 2 mm needle once every fortnight.