No, that is fine. I always put mine in through the skimmer. You'll need to keep your pump running 24/7 for the next 4 or 5 days and don't backwash or you'll just throw the CYA out. It is slow-dissolving so don't test for it for about a week.

EDIT --- After re-reading I wasn't sure; when you say that you just poured it in slowly, you did mean that you poured it into the skimmer, right?