Can Taking Norethisterone To Delay Periods Be Safe?

Hi, may I answer your health queries right now ? Please type your query here...hi I have norethisterone to delay my period while on holiday next month, I don't know when to start taking it because my period is never exactly regular, this month it's come four days early how can I work out when to take it? I'm away for a week and only have enough tablets for 11 days my period is due roughly half way through the week if it comes on time. Thanks