I'm coming in late on this one but on the subject of beginning the takeoff roll with dive brakes extended, maybe it's worth repeating some old advice. At least on Standard Class gliders (i.e., no flap handle), the easy way to reassure wing runners (and tow pilots) that the pilot hasn't simply forgotten to close/lock the brakes is to cycle them in and out repeatedly as the slack comes out of the rope. Yeah, it's a bit of a hassle but as the rope tightens you can hold them out to actuate the wheel brake if that's desired.

By now, everyone including the ops director, wing runner, tow pilot, spectators, the pilots behind you, and birds flying overhead will be aware that you're doing it intentionally and not forgetfully. And if the wing runner looks puzzled, I just cycle them one more time after the thumbs up signal.

Chip Bearden
ASW 24 "JB"
U.S.A.