How Long Does It Take To Start Periods After Taking Medroxyprogesterone?

My husband and I are trying to get pregnant and I am now four weeks late so I went to the doctor because My pregnancy test were neg. He put me on Medroxyprogesterone 10mg for five days and it has been four days since I have taken the last pill and still now period. How long after does it usually take till my period should start?