B/f and i may break up soon! or not see each other for awhile! i am going to go on birth control ?

the birth control is so that i don't wind up gettting pregnant! we been using condoms but one broke and i don't want to take chances like that anymore, i have niever uesd birth control of any kind except condoms. so my question is with my relationship in limbo should i just go ahead and get the scrip from my gyno and start using it, or should i wait to star t using it unilt about a week or so before i know we will be getting togehter so that i am not putting the chems into my body unessacaliy? if were not gonna be having what is the point to my starting myself on birth control until i know we will be having s?