I heard. "When you read a good book through the second time, you don't see something in it that you didn't see before, you see something in yourself that wasn't there before."
'Ready' means your awareness, the primordial intelligence as Eckhart Tolle says. As your awareness level goes up, you will meet new teachers based on the level you are at. So, new teachers will appear as your level goes up. There is no limit.