Is It Normal To Have Early Periods After Taking Postinor 2?

Doctor,a frd of mine tuk postinor 2 n instead of seeing her period on d 25 of last month,she saw it on d 13,n it jst lasted less dan 5days,2 see it again dis month she waited 4 d day it stoped so dat it can start again dis month but it didn t come n now she wants 2 wait till d normal 25th.what do u tink sir.tnks