As a PT the ususal advice given is 6 weeks and provided you have had the all clear at your post natal check up.
It depends on how you have healed and if the muscles that seperated (just below the rib cage) to allow your womb to expand have closed up successfully? A health visitor or midwife or specialist pilates or exercise teacher should be able to check this but here is a link for a self test!
https://www.sharecare.com/health/la...iod-of-pregnancy/how-can-tell-diastasis-recti
If you have a 3 month old to care for then I assume you are up and performing the usual twisting, turning, bending down and up type movements without pain?
Then it depends on what you are trying to achieve but as with anyone who hasn't done anything to rigorous recently and is probably sleep deprived I'd say start gently (walk before running or jumping around and testing those pelvic floor muscles) but really enjoy the time to focus on your body and feel in control of it agani. Be kind to yourself about getting back to where you were before too.
I am type 1 and have had 3 c sections which I recovered from well. Having 2 other kids/work probably stopped me mroe than my physical condition but I loved just getting away from the mum zone by going for a run via a coffee shop!