I counsel patience.
I had a cervical fusion and two artificial discs implanted in 2008. It was done in a Army hospital and I was cleared for a 100 lb ruck, which would never have considered trying to carry, after maybe 8 weeks. During the post-op period, I walked miles and miles and spent a lot of time in the gym doing the prescribed work and fixing some incidentally-uncovered strength deficits, so the fitness loss didn't seem so terrible.
The limiting factor, at least in my case, was re-ossification around the implanted hardware, particularly the fusion, as determined by X-ray findings. Once that was good, there were no further concerns. Surgeons are cautious by training, but I would definitely talk to your rehab providers before pushing the envelope. Setbacks can be long and serious.