Most protocols for hair restoration surgery recommend stopping many supplements for varied amounts of time prior to surgery and then resuming at a specified time afterward. You should refer to the documentation given by your hair restoration provider. All that being said, it is safe to resume...
It is not uncommon for growth to start 4-6 months after hair transplant. By 6 months, you should begin to see growth, so if you are at 5 months post-surgery then I would monitor a little longer. If you do not notice growth at 6 months then I would follow-up with your surgeon.