Start to learn piano at 16 is not late. I've learnt piano at 20 and after 1year, I passed grade 3 . one and a half yr later , I passed grade 5.
However, if u really mean to learn it, u better buy a piano and practice at home. At first, may be 30 to 45 mins.daily. When u go further higher grades, u have to practice more. But, to practice daily is important as well as to find a gd. teacher.