How long would it take me to get at least 4 pack abs?

Hi, i am 17, 155 lbs, 5'10 tall and I used to be fat so i have some fats. I work out at gym every other day and before lifting weights we do abs exercise we do lots of crunches, sit ups fish flaps and a bunch more. So I was wondering how long would take me to get at least 4 packs??