It depends upon the child. It was okay for my DS7 (though I suspect he was kind of obnoxious about knowing all the answers...), but different kids are totally different.

Even that small amount of time can turn some kids off, but some are fine with it.

Did you visit the school with her? If so, did she get the chance to be part of the group and actually try out circle time, not just to observe? If not, I'd recommend a visit that gives her that opportunity. You can see how she reacts.

Kriston