My DD had it, no problems.
My hubby took it a couple of years ago since he was worried about getting them as an adult, since with kiddos, you tend to be around kids who are infected and don't know it yet.
Case in point -- my DS, who I was sure had had the shot got them at the end of last year from who knows where. I was in denial at the first sign. I dug out his old shot records and realized he'd never gotten it! (He was born in 93 and it wasn't standard for kids to get them until 95, I think.) Poor baby was miserable for a week, thanks to mom's oversight.
I'd rescuedule if you can, but if not, just bring the tylenol in case they start to feel bad.
If I remember correctly, they wanted to recheck my hubby's blood in 10 years, but then his doctor told him he wouldn't need to when he showed up with a case of the shingles last year
You can only get the singles if you have the chicken pox antibody in your blood.