What kind of aircraft are we talking about? What does your POH say?

In C-152s and 172s, I've always taught holding the brakes until max power is established, then release. I suppose I taught this mainly because it's how I was taught, and it's what I believed the DEs would expect.

In practice, I've done it this way because most of the short fields I've taken off from were also high-altitude fields, and I wanted to lean the mixture for max power prior to brake release.