20 pages per day is all you need to read. If you do that you will be able to read approx 500 pages or more per month. Which is equals to 2 to 3 books per month as usually (if book is 200 to 300 pages approx).
Book reading is the best habit you can cultivate. But its very difficult to implement hence keep your target small. 20 page per day is not much it will take 15 to 20 min per day. So make sure you give your self 20 min per day which will help your growth immensely.
As said by George R.R. Martin: “A reader lives a thousand lives before he dies. The man who never reads lives only one.“