Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Sudden severe neurologic symptoms, paralysis, or loss of bladder or bowel control require emergency assessment rather than a routine appointment.
Routine follow-up is appropriate when pain persists, repeatedly returns, or limits sleep, work, or normal activities.
Contact a clinician if symptoms do not improve with initial care or if medicine causes side effects.
Follow-up may review function as well as pain.
Useful changes to track include whether arm symptoms are spreading, whether grip feels weaker, and whether walking or hand coordination has changed.
The article also says
Seek an earlier medical review for:
New or increasing arm or leg weakness
Worsening numbness
New hand clumsiness
Increasing falls, poor balance, or walking difficulty
Fever, unexplained weight loss, or pain that is severe at rest
Symptoms beginning after a significant injury
Every sign above is quoted from the sofidex article on Cervical spondylosis. If you are not sure, err upward — it is always reasonable to be checked.