5mm - 1/2 a cm. Keep in mind, because you've been shaving, you'll have a second hair growth coming through so you wont have that "silky smooth" feeling the first couple of times you wax. It takes a few times of waxing before they will all come out together as the hair grows in three different stages. Good luck! P.S. I think bikini hurts way less than legs
Also, make sure you exfoliate really well leading up to the day of your appt. and dont apply any moisturiser to the areas the morning of your wax.