I was back on my mtb riding Brechfa black trail on the 12th or 13th day after the operation. I was 27 at the time so a good 5 years ago now.
I had keyhole surgery for inguinal hernia, first few days I really regretted the operation, painful to walk, had to sleep on my back and general discomfort.
You really take for granted how much you use those muscles in that area, getting out of bed was a struggle, think I spent the first few days just mixing between laying down and sitting on the sofa.
After the initial first days I seemed to recover very fast,was walking around a lot more up and down the stairs became a lot easier.
whatever you do, dont sneeze!
Listen to your body, you will know if your ready to go back out riding.