I took up the piano at age 16 (never played a musical instrument before then). For 4 years after high school I did little beside practise, going to lessons, listening to music, and reading everything I could get my hands on about playing the piano. (I also kept a part time job in order to pay for lessons books CDs etc.) At the end of those 4 years I had my AMusA and passed my university audition. It's definitely possible but not easy. I had to be pretty single minded about it to make up for lost time.
How did you fare with nerves when doing recitals/performing? Most people I know of who are comfortable with that have been performing since they were 2 and a half haha