I’m going to echo @TrinityBringer on this. Everyone has their own learning speed and style, so there are no absolutes, but I’m thinking you’ll want to start reading native material waaaaay before level 60.
Reading is one of the best ways to get used to grammar, and ultimately to be able to recognize it immediately on sight. Some people can read a textbook and understand the grammar and retain it. For someone like me, I can’t fully grasp it until I see it in something I’m reading, and I can’t retain it until I’ve encountered it multiple times.
P.S. We have book clubs.