I don't think starting with the rotary is an issue under certain circumstances. For me, I first learned on a rotary...but I had someone helping me out and giving me tips.
As far as going into using a rotary blindly...I wouldn't recommend it. But, that doesn't mean you can't do it. It's certainly not rocket science. If you go slow, and educate yourself on how to correctly use products, and focus on technique...you should be just fine.
If you are planning on experimenting with a rotary on a customers vehicle...THAT I would stay far away from. You don't want to do that for sure. You will make mistakes. You will get puzzled, and you'll have to figure it out. But, you may need some advice, or tips before you figure out why that vehicle is swirled, and what you have to do to fix it. So, just leave a customer out of it...and you're all good.
The main issue is keeping control of the buffer. You guide the buffer...you don't force it, and you don't let it get away. A rotary is a piece of cake to operate once you get a feel for it. You should be able to glide a buffer around the hood of a vehicle with one hand effortlessly (not that you should, but you know what I mean). Practice your technique with a glaze and a soft pad. Once you're comfortable, experiment with compound, different pads, swirl remover, sealant, etc, etc. You'll get it down! Good luck.:dblthumb2: