In reply to wcote: Hopefully you will have had physio and done lots of stretching and strength building exercises during that year...
Rather than bouldering, why don't you start by doing easy routes at a climbing wall. Bouldering is fairly intense. As has been said your body is the best feedback. However, I don't see any problem with 3 sessions a week but keep them short to begin with and of low intensity.
You may also benefit by doing some easy weights, pressups, pullups, hangs etc. These can be done in a very controlled way.