Bead glaze questions

I recently purchased a bead glaze to experiment with. I am wondering about the application process: should I first apply an underglaze (after the first bisque fire of course) and fire the piece, followed by a separate firing for the bead glaze? I've attempted this process once, but the glaze didn't bead up as expected under the correct cone. I put the under glaze and bead glaze on at the same. Any advice on how to achieve the desired result would be appreciated.