I waited the full 6 weeks
It was a lesson in patience both times.
Very frustrating. I had my husband drive me to barn to walk around and I would groom and and walk. Because I was not allowed to be in the front seat due to the seat belt on the belly.
Once or twice I brought the baby in the stroller meant for off road and pushed the baby while leading the horse. With a friend of course! Anyway, horse could care less about the stroller
The walking helped me gain strength. I was surprised how much core strength was gone, just walking! I was afraid to lunge, only if the horse acted up & I needed to hang on it wasn’t going to happen.
I walked every day around my neighborhood, with the dogs for motivation. I built up to a good 45 min-1 hour brisk walk. My first C was horrible. Emergency C after a long labor, drugs made be ill, I got a UTI then a bladder infection then another UTI. I was very sick for at least 3 weeks after delivery, which contributed to being on “stall rest”. When I started walking, I could not make it down the block without stopping and crying! The abdominal pain was incredible and lasted for a long time. I could not take pain killers because I was breast feeding, not even Tylenol. It was a very awful time!
The second one was easy breezy, no complications, and I was back to my regular self inside a couple of weeks. Or whatever passes for normal with a newborn!
My advice it to wait. If you tear those muscles again they take a long time to heal because you use them for everything! My OB-GYN was very clear on this on my weekly visits. Getting the staples out was a mile stone!
When I finally got the pass to start riding it was like starting all over again. I stopped riding at 6 & 5 1/2 months, respectively. So I had not ridden in almost 4 months. Longer really because at the end I was really just taking it easy. I used to look at my watch and be like “OMG! Has it only been 5 minutes of posting trot! I want to get off!” Everything was off. Everything hurt 
If you have a change to go to a gym when you get the all clear go for it.
Other than that go to the barn, groom, hand walk, turn out if he behaves. Just spend time bonding with him and hanging with your barn friends if that is part of your scene. Not worth the risk IMO.
It will pass!