I'm not an expert on speeches or anything, but the idea with the start is obviously to capture your audience, so, you can pretty much do whatever you want with it as long as its interesting enough and shocking enough that it makes the audience want to listen to you. I think with this, the more original it is, the better. Especially if its a school speech and they have to listen to 100 other people get up and do exactly the same thing. Anecdotes or hypotheticals work well, especially when you pair that with manipulation of emotion and putting the audience in the situation that you're trying to argue, make them know how it feels to be on the bad side of what you're trying to argue! You can team this up with some sick statistics or examples to make it sound like you know your shit. As I said, Im no expert, but, if you want any help, you can message me and I'll see what I can do!
ALSO - totally forgot to add this, The whole idea with the start of it is to grab the audience's attention, MAKE THEM WANT TO LISTEN!
So, I'm not sure if this is the way you're meant to do it, but this is the way I have always done speeches, instead of being like:
Hello, my name is blah blah and Im talking about this
BAM ANECDOTE (The anecdote has lost its purpose, your audience isnt listening due to your boring intro..)
So instead, you start with the shocking, crazy ass anecdote, and wow your audience, make them pay full attention to you, and THEN move on to introducing yourself.