I had a fusion on C4-5-6 9yrs ago. I wasn't playing pool at the time but I think it was over 6 months before the doc told me I was good to go and do most anything.
I have to limit practice to about 2 hours as usually I will get headaches from the constantly tilting my head back. It takes much longer for a headache to develop when playing someone so, that's usually not an issue.
BTW the correction/fusion for my herniated disk did nothing to correct the problem of compressing nerves going to my right arm and hand. (pain and atrophy) Wish you better results.