You might find extra spools used pretty cheap, I suppose you could cut a strip of paper to practice with?? (since you'll be loading paper backed film anyway, might give you a feel for it). Besides
ebay you could try Pittsburgh Camera Exchange, or maybe Pacific Rim Camera (not sure if they have small odds & ends or not), or the Columbus Camera Group. Or if you get film cheap enough you could just try a roll, I've done the same thing as 'Coop, you could advance it to #2 anyway if you want to make sure you didn't expose the first frame.
Don't remember if I mentioned FPP before, I think they have a video on how to load 120 film.
http://www.filmphotographyproject on their site, they have a YouTube channel too.
I don't think 116 has been made in a long time, it would be really fogged so you might have to do an awfully long exposure to expose it long enough to get anything. However I've seen things about people adapting the 120 spools to fit, they cut circles out of foam (like old computer mouse pads, which might be too narrow for this), and place the circles at each end of each spool to hold it in place. Not sure how well it would work, and you'd have sprocket holes (edge of the film showing) in your images, which of course you could crop out but they can be kind of cool looking, just allow for that when you frame shots (that you may 'lose' part of the image you see in your viewfinder).
Film for Classics used to respool and sell odd sized film, but I don't think they sell direct anymore, you could try
B&H or maybe
Adorama, or I think Central Camera in Chicago carries it (odd sizes, but it's not cheap, and I can't remember if they did 116). Not sure either if anyplace can develop 116 unless you're doing your own. So I don't know, maybe the 116 camera will be shelf art and you could start with 120 and 620.