Disc Wheel Magnet

My new disc is due in today. I use a Cateye Astrale Computer cadende and rear mount. A couple questions on this board reminded me that I need to figure out how to mount the magnet to the disc. Will the glue on the back of the HED3 magnet kit hold it to the disc or will it come flying off and hit me in the as#??? How have you made it work?

See the recent post on how to mount magnet on Hed 3 wheel
.