Don’t scare the young padawans!
That’s just you being crazy! 
If you do like me, alternate between going faster and slower at the “fast levels” you shouldn’t have more than 200 reviews daily, though I do have a bigger load this day. But, you definitely don’t have to get completely buried in reviews unless you like it that way! ^^;
As for reading. I started reading stuff long before I started my WK journey. I’ve also listened to Audio Dramas, podcasts, watched some Japanese anime, tv and movies, read some news, played games in Japanese…and so on. All before WK.
I don’t think there is a too soon for any of these thing - if you have the patience for it.
That’s really the only thing stopping you, because you’ll have to look up a lot of words.
Also, depending on how well your grasp is of grammar is, that could be a road block. But I started reading with just some very basic grammar comprehension also. 
At the very least, give reading a try.
And if you feel it’s too challenging, just try something else. But, getting into reading and consuming Japanese media is a great way to support what you’re learning through WK. These things go hand in hand. 
Good luck! 