Period Delay Tablets

Hi guys i’ve bought some tablets online from a pharmacy called Norethisterone. I’m using them to delay my period for just 1 month. I’ve never used them before so i’m just wondering what your side effects from them were. My long distance boyfriends coming for a few days and i happen to be on my period when he’s coming which is abit of a killer as we only see eachother twice a year.