I wouldn't cut the stem off to start with (well, ok, maybe you'd want to trim it a little!). I spend AGES the first time I used it just trying to get the stem length right so I could "reach" it easily enough but not be in agony because it was too long. Having said that, I ended up virtually cutting the whole darn thing off anyway, so felt like a bit of a waste of time!!
As for getting used to it, I found I'd actually gotten used to using it by the end of a period without having practiced with it at all before period started. And I too found I didn't need to change it half as often as I did with tampons.
And finally, how to distract a toddler .... I could do with tips on that one too please!!
xx