The way I would see it two bath development under your eye is the way to start. Even such a camera like this Pentax is not foolproof and too quick triggering may cause under exposure. I've seen that. Once they know how to take pictures, basics of development and how looks printable negative they may graduate to more demanding developers, where time and temperature control is more demanding. Knowing, how looks good neg and knowing, that the camera is working OK they may correct own developing mistakes and eventually graduate to the next step: understanding the exposure and move to more manual equipment. With 120 I would wait until there is more experience with loading the reels. Even "cheaters reels" are not easy to load with 120, maybe even harder, than Hewes reels. Off course black out closet is 1000 times better, than changing bag.