Please Help: articleship

i am the students of ca final,and i was registered for my articleship as on 1st may 2008,but till date i have not take the service certificate from my principal,my query is that can i serve more than the fixed period ie. 365 days and correspondingly i will be eligibble for more leave.
my 2nd question is that any time limit under i have to deposit the service certificate to the institute.
thanks in advance