Unfortunately, there is no clear cut answer to this.
I partially tore my UCL in the fall of my sophomore year of high school. My doctor had me wait until the spring to throw again and luckily I never needed TJ surgery. My elbow would act up from time to time and I would have some ulnar nerve issues occassionally but the ligament held up through college. When I had my shoulder done up after college, the MRI of my elbow showed the scar tissue on my UCL but it was still in tact.
While rest doesn't work for everyone I would suggest you try that first. TJ surgery success rates have gone up but its still not a full proof procedure.