How long will it take to become good at piano?
My first piece of advice, if you are really serious, is to forget the keyboard: buy a real good used piano, if you are unable to afford a new one. Keyboards in my opinion are strictly for the birds: they simply do not have the “feel” of a real piano. You just don’t want to “start out” with one: trust me on this. Unless you are another Mozart or Van Cliburn, learning how to play the piano is very similar to any other learning process. The speed at which you develop your skills, depends primarily on the following: (1) and this is most important: a good competent teacher. (2) the degree to which you apply yourself. (3) and above all, how much and how dedicated and thorough is your practice. It should be very often – at least an hour or two(every day of the week), preferably at a regular, set, given time. That it be continuous; no running to answer the door or phone. No snacking, no intermittent conversation with anyone(other than your instructor), etc., etc., etc.