Replying to Morning after pill

Alright so yeah, shit happens, had to go get my girl the morning after pill the next day, $45 fucking dollars too. Im still scared shitless and tryin really hard not to think about it. I dont know much about it but whats the first sign that it worked? If she gets sick the next day? Any feedback on people that have been in my shoes would really help..also it was about 2 weeks after her period that it happend dont know if that means anything