I've recently amended my criteria for cutting the cord. My current students must:

1. Hand me the transmitter, plugged in, with antenna extended. (good habit. A former student forgot to extend antenna, because I had been doing it.)
2. Start the engine personally, walk behind the wing, retrieve glow starter, and free the plane from the restraint.
(all the above, every flight, starting with the first, when I help with the details.)
3. Perform takeoffs & landings without me touching the sticks.
4. Complete some stall training at high altitude, with adequate recovery - again without getting me concerned..
5. Remember to pull the throttle back when I get them in trouble and switch control to them.
6. Do some adequate rolls and loops, with the training plane.
7. Cope with crosswind landings - plenty of that this year!

At that point, I'm just standing there watching, so they might as well solo! I don't walk away when I hand them the transmitter, though, I stand there with them. Seems to give 'em confidence.

Good luck,
Dave Olson