How long SHOULD I wait?

After having a miscarriage I feel I want to start trying again ASAP. The nurse at the hospital advised I wait one cycle, however if I started trying again before that, is there a any medical reason why I shouldn't? I know mentally trying again will be better for me and DH and get us back to normal, but physically if I did get pregnant before that could I be putting a future pregnancy at more risk or is the waiting one cycle more for dating purposes? would appreciate any advice/experience people may have. Thanks.