Well, for one, the actual threshold for qualifying for premium/rewards/etc has never been released. We don't know that it's exactly 1,000.
For another thing, the number of downloads doesn't matter. What matters is the number of people using the Curse Client who have your addon installed. If it was just downloads, it would be too easy to game the system by setting up a bot to download your addon over and over. :p
Weird, could've sworn the little FAQ thing said the threshold was around a thousand. Oh well, I can wait. Was thinking I might've screwed something up somewhere. Like the Rewards/Points program...didn't realize you opted into it.
And yeah, I've been signed up for the Author Rewards for a while now
the number of people using the Curse Client who have your addon installed
This is OT but I think the OP's question was answered and others might be curious about this too:
Is there a way for addon authors to see that number of current installs for each of their addons? I can sort of guess at it based on the number of downloads of each released version, but it'd be cool to actually have a concrete "install base" number (minus, of course, people who installed manually or from another distribution site, if applicable).
Also, as far as the bot goes, I don't think that would even work. My fiancee uses the addon and when she updates it, the download count doesn't change (we're on the same network), so they probably filter IPs for the day or some such thing. Which, if that's the case, that's rather smart on the developers' part. Anywho, just wanted to point that out
I got an email late February that the complementary premium subscription for authors got extended, but some time the recently it disappeared and I get a signup page on curse when I try to check my status.