It typically takes about 20 minutes for hot rollers to curl your hair. This amount of time allows for the curls to really set in and stay put all day. If you want less curl but more wave, you can pull them out at 10 minutes. And if you have especially hard to curl hair, you may need to increase to 30 minutes. In general, the longer you leave the hot rollers in, the curlier the hair. Just always keep in mind that if you don't leave the rollers long enough, the curl may not last as long as you'd like either.