It took me 6 months to do my first v6. I think I remember every part of that route (it was almost 3 years ago), and the feeling I had when I was about to match the top hold.
My goal was to go up a grade every month. That stopped at that v6, though.
Since then, I have moved to a different gym, and in this gym, the grades are much softer. There are new climbers that can do many of the v6 routes, and they have been climbing for just a few months. So it really depends on the route setters, and if they are soft grades or not.
The shoes I used in the beginning were relatively very cheap, and very basic, very beginner level. I used them for 6 months until I basically had to get new ones because they were full of holes and the rubber was almost non-existent.
I will say though that I am happy I bought those shoes. They were cheap, and I believe that any pair of shoes that I would have bought would have been destroyed as well, since when I started climbing I had no knowledge or experience in climbing, so my technique was awful, which caused the shoes to get ruined much quicker.
Also, just to point this out since the question may refer to the grade at which the beginner shoes were swapped with more advanced ones, I climbed in those beginner shoes with all of the holes until I could do a few v6's, and I only climbed indoor boulders.