Just wait a few levels… you’ll see it start since you’ll have a couple items in the queue.
Read section 2 of the Ultimate Guide to WK… you can easily get in the hundreds of reviews per day and seven-days per level if you really want to go for the record speed! 
But, honestly, remember that tons of reviews would take hours per day, so it’s really not that great (remember that 1000 reviews is almost 2000 questions: meaning & reading)
If you go lightning-speed on them and only take 6 seconds per half, and never get anything wrong, then:
(We’re assuming radicals aren’t a significant factor - out of these 1000 reviews, only 37 are radicals, so we can just ignore them to make math easier)
2000 halves * 6 seconds = 12,000 seconds = 200 minutes = 3 ⅓ hours
But, let’s be real, you won’t go that fast, and you will get things wrong, so:
2000 halves * 1.5 (for re-answering) * 10 seconds = 30,000 seconds = 500 minutes = 8 ⅓ hours
Maybe. If you’re lucky, since you just built up 1000 reviews…
The point is that you don’t really want that much!
At maximum speed with perfect accuracy (credit goes to whoever @jprspereira got it from):
