Was due for my top up depo on the 14 dec,but we r going to try 4 baby num 3,not had a period yet.?

hav had a white creamy dis charge,and small diging pains in my overy area,was advised to start takeing frolic acid,as this will help prepair my body when i fall,what i would like to know is ,does anyone know how long it could be till i fall.was on depo for 2/half years.with my boys it only tock 8 weeks to fall,but i was on the pill then.