When is it time to have spinal surgery?

This really depends on the underlying condition. In most degenerative spinal conditions, the decision to have surgery is based on a multitude of factors and for the most part delay does not militate against a successful outcome. Caveats include conditions which result in deteriorating nerve function such that there is a precipitous decline in function.

The ultimate decision to have surgery is a subjective and personal decision and should be reached after careful delibraition and discourse with all parties involved.