not 3 years,
you must have registered as a trainee atleast for a period of one year, and must complete minimum 6 months of training to appear for final exams, w.e.f.Dec.2013..
and 6months trng to be completed by 31st Mar or by 30th Sep.. for June or Dec exams...resply.
for more details, check this link..
https://students.icwai.org/Training/docs/Circular31-01-2012.pdf
All the best:)