plan b

my boyfriend and i were having sex without a condom. it was our third time having sex without one that day. but the last time he was pulling out but it slipped back in and he came in me. we both noticed right away and started talking about what we should do. so we ended up going to get plan b an hour later. on the plan b box it said the quicker you take it after unprotected sex the better it works. that was about a week ago, my period is suppose to come on the first of feb, should i wait to see if my period is late? or take a pregnancy test? do any of you have experience plan b?