From personal experience and given your status that you have sufficient funds and will sponsor their trip, I don't think it should be any difficult for you to get them to visit you. Mairie de Paris does take time (at the max 2-3 weeks) but 2-3 months is a bit exagerated, I think.
I have got the attestation d'acceuil done twice on different occasions for visiting family members. However, my cousin had a problem (I wasn't sponsoring his trip, he was coming over for an internship at a French university) with the French embassy in India. It was not about the time but he had to appear for a couple of interviews, it seems. That's about the botheration of it all once your papers and financial status are in order.
Having your wife and kid visit you is the most natural thing, no mairie or embassy have the right to delay their travel unnecessarily
