When do i know if im ready?

i just needed a little help with my situation. i curently have a boyfriend that ive been going out with for one month. we are both 19 and havent done anythign but kiss. now im still a virgin and wasnt sure how many months should i wait or how i will know when im ready. hes really like my first boyfriend and i have a feling we are going to be togather for a while. so i guess my question is what is a typical wait time that most girls my age wait util?