Resume exercise

Mummies, how do you know when you can resume normal exercise regime (including ab work)? I have ab separation and have been doing post natal pilates and barre classes and avoiding ab work. But I don’t know how long it takes before I can resume normal classes rather than postnatal classes. I’m 4 months pp now. And for those who says gynae to advise, my gynae does not advise; she didn’t even help me check for ab separation and said I can easily check it myself. Dying to get fit again.