It's difficult to say without knowing your situation. Personally I would wait a few months at least to be sure that the biggest bugs are killed. Then if it's a new project or something not critical, I may upgrade without any precaution and hope for the best. For something more critical I would rely on the integration tests and manual testing in a pro-production environment for a few weeks. Before the final upgrade, I would finally do a few practice upgrade runs and be ready to rollback if needed.