Advice on RH- Hope this is the right place to ask!

So I’m ORH- && found out with my first full term child. We lost a baby about 5 years ago due to a miscarriage. We have a beautiful little girl that will be 3 in June. We are wanting to have another baby. I know I have to get the RhoGam at like 28 weeks && again after I have the baby, at least I did with my daughter. Does anyone know if I need to get the shot before we start TTC? I go to the doctor for a fertility consultation Wednesday. But I’m just trying to see if anyone is like me && TTC again! Any comments will help!