From my experience, which was only a spinal fusion and some stenosis clean-up, I'd say a year of recovery will be needed. You're doing the right thing--get as much exercise as you can bear and do as mNT strengthening exercises for your core as possible.
Thanks for that. You walked the AT subsequently. I get more "bold" (within reason) which feeds into progress on the road to recovery/repair. PT often brings up attention to core importance. Not that it's desired but I couldn't do a sit-up for the life of me. They used to be part & parcel of exercise at the Y etc.
I hiked the AT in 2016 and had the back surgery in November, 2018. I'm pretty happy with my recovery and there are days when I completely forget about the lower back, i.e., it's free of any pain or aches.
Sit-ups weren't part of my PT core exercises, seems they aren't good for those who have had spinal fusion. But planks are OK.
I was told that sit-ups are bad for anybody with lower back issues. Do bridges, planks, strengthen inner/outer thighs, etc.
Sit ups are part of bygone youth it seems (when we could do most anything). I wondered about the order Fred. Recalled the AT easily so assumed it was probably more recent. It was one heck of a walk, a nice achievement.