It's been a while since I taught anyone to juggle, but I generally disrecommended scarf juggling. It's fine if you want some quick validation, but the hand movements are so different from balls/bags that I don't think the skills are transferable.
I prefer the method described in the original post. Just start with one ball and get that right, then two, then three. It's a bit like the Karate Kid, though. Students don't find it as satisfying because they want to jump ahead before they've got the movement down.
The scarves I use, as I mentioned in another thread, are actually weighted. They fall more like a traditional ball, just significantly slower. I’ve found that this works pretty well for teaching, but of course everyone learns differently.