Only took me a day or two to get on par and better with the tablet than I ever was with the mouse. Though it's not like I played the entire days. In total it was maybe about 2-3 hours of play time. The first few songs on tablet made me feel like it was pointless and that I should just quit and go back to the mouse. But I'm stubborn enough and kept playing anyways, trying out positioning and pen holds, and eventually I got it down to where I could play comfortably and smoothly.
I'm still an awful and shitty player compared to everyone else. So even though I've improved more with the tablet, it's nothing anyone else would care about, me being so low in rank and all. But I have fun with it and that's what matters.