That depends. I overwintered my container blueberries in the garage this year, and because of the warm winter they budded over a month ago. Now they have leaves and they are flowering. Others who had theirs in the ground or overwintered them outdoors, were a month later than mine.

It all depends. I have a customer who has an old blueberry bush that had little flowers opening all over it last friday(DE).

My Rabbiteye has just started opening its leaves in the last 2 weeks or so. They are not nearly fully open yet though, and some are still just buds.(DE)

In zone 4, you should be well behind us, and you may not even have full formed leaf buds yet. I'd give it time.

thx guys. I'll give it another couple of weeks.