FawkesthePhoenix wrote:"I've tried a few simple spells myself, and they've all worked for me."
how could hermione try spells before going to hogwarts? she's a muggle-born, so the ministry would know if she tried to do magic when she's at home!
Like all young wizards and witches, she realized she could do magic (or make something odd happen) early on.
I always just assumed that the day she got her letter, she began learning about everything magical she could (she started out knowing as much -- in theory -- as Ron or any other pureblood magical person knew practically).
The way I imagined it, she got her books, and her wand, and everything immediately. After all, this is Hermione, and she would want to begin learning everything immediately. I figured she found out about how it was illegal to practice magic outside Hogwarts at her age, around Muggles, after trying out a few simple spells for herself.
I also have a theory about just how strong "The Trace" is, or how it works. It is apparently illegal to practice magic AFTER you've began to be trained in it. Before that, the Ministry didn't seem to think it was enough of a threat, or they didn't think there was a way to enforce (something any parent can appreciate -- you cannot always just MAKE your children do the right thing).
Up to a certain point, the Ministry may KNOW about magic performed by children under the age of 11, but they don't apparently DO anything about it. It's mentioned often how it's perfectly normal for the children to accidently perform magic.
However, in at least three other situations, we know of children not old enough for Hogwarts casting spells on purpose. The little boy at the Quidditch World Cup was casting a spell, with a wand, to engorge a caterpillar (or worm, can't remember).
Also, Fred and/or George cast a spell on Ron's teddy bear at a very early age, and Ginny is an accomplished Bat-Bogey Hex-er at a very young age.
There's no mention of the Ministry getting involved, or even having a problem with it.
I don't think underage magic is actually considered illegal until after they begin to be properly trained. Part of the training is in gaining self-control and respecting your magical powers.