The rash showed up on my thigh after a day or two of what felt like it might be sciatica. Your mileage may vary, but it really threw me for a loop. By the time I figured out what I had, it was too late for the vaccine. The rash looked bad, but frankly, it was the least of my problems. The worst was the pain up and down my leg that made walking difficult and sleeping even more so. That and a low grade fever really took the wind out of my sails for more than a month.
By the way, “shingles” seems like a weird name for this condition until you realize it has nothing to do with the slabs on your roof. It comes from the Latin word cingulum, which means “girdle.” The Germans have an even more literal name for the virus, Gürtelrose, which translates as “red girdle.”