When I started osu!, I played a small amount of easy maps before moving to hard maps. I remember the last hard map I ever played was Nehanshika. After that I swapped to tablet + keyboard and my accuracy started going down, but eventually I became better and reached my current (93.39%) accuracy. I guess if I were to estimate, it would have taken me about 1.5-2 months before I started insanes. I mostly stick to insanes which I can pass in an effort to raise my PP though, and I'm currently playing barely passable songs (at least for me), so my PP is dropping fast.