I had that done so long ago I forget the exact time frame, but the Dr should tell you exactly when in her cycle he wants her to have it done. They also say that sometime this can increase your (her) fertility b/c it is kinda cleaning out the tubes as well. I'd have her call the office to find out when the dr normally likes to do an HSG in her cycle? It is a pretty routine test before starting fertility treatments for most practices. Good luck!