implant/pregnant

about a month ago July 23 I got the arm implant and i only waited 3 days as opposed to the 7 to have sex. They told me it was effective immediate but that they’ll also recommend i wait so my body gets used to it. Could it be possible i would’ve gotten pregnant? I was supposed to get my period today but sometimes it’s late so idk if i’m just worrying too much, because my periods could also completely stop and be irregular?! idk what to do or feel or think ugh