Do you get points for leftover tokens; this time being the notebooks? Or is it something where you can just hoard it til you're ready to grind out the event song?
They're only good for playing the event song. You can hoard them all, or spend them as you receive them, there's no real difference, at least for the NA version.
Why do I say the NA version? Well, the JP version has a feature where you get double the points for double the tokens spent, usually a few days before the event ends. No, you won't get more points using your tokens this way, but it does help you burn through them faster, which may or may not be a good thing [depending on if you're going for the play bonuses for the event song].
Also, you don't get points for leftover tokens. Anything remaining at the end of the event is simply discarded.