Chocolate cyst treatment. Every month) ?

My wife has two chocolate cysts in her right ovary. Our gynec had suggested an injection- Lupride Depot 3.75 for three months to reduce the size of cysts so that ovarian wall/tissues are not damaged during surgery to avoid infertility. My wife's latest period date is 19-Aug -2016 (yesterday). Her previous period date was 01-Aug-2016 and we applied the injection on 05-Aug-2016 (i.e. within five days of period date). Her latest period has come early this time. I asked our gynec to order and apply the second injection of Lupride Depot 3.75 today, but she said this injection cannot be taken so early, it has to be taken on 05-Sept-2016 (i.e. same date as last month). Now we are confused if this injection needs to be taken within five days of period date or exactly once in a month (same date every month)?