Pre op my doctor said that it would be okay to start driving 6 weeks after surgery. Post op, he told me that 4 weeks would be okay but that I should decide for myself when I was ready. He said to take the car around the block a few times to begin with instead of attempting a cross-country trip
Although I probably could have started driving at 4 weeks, I waited until 6. My mom moved in with my kids and me after surgery, so I had the luxury of having a chauffeur (LOL) and I didn't really have any incentive or any need to drive. I had enough I was dealing with - fatigue, balance issues, SSD - so I waited a little longer. If I wouldn't have had anyone available to drive me and my kids, I probably would have started driving earlier.
Everyone is different. Once your doctor gives you the okay, you should pretty much know if you can reasonably try it or not.