Hi thanks for your question.
It takes about 3 month for your body to adjust to Depo provera
.Your body needs to get used to hormone progestrone
which is content of Depo provera,similair to other hormonal
birth control pill.As your body is adjusting to Depo provera .It is likely that you will experience spotting (irregularbleeding) or prolonged heavy bleeding like periods .This is considered normal However if bleeding is very heavy consult your gynaecologist.
Hope this answers your question.