Shoaib, you will get 120 days to submit your application from the day you get the AOR through email. There are couple versions of story floating around regarding when exactly the visa will open our file
Assuming you receive AOR from NS on Dec 31 and they say you have 120 days to submit the complete set of application, this means, you have time till April 30 to submit the application. But, if you send your complete documents on Jan 4:
Version 1 of the story I am hearing is, Visa officer won't touch your file until April 30 even though you submitted the documents 110 days earlier.
Version 2 of the story I am hearing is, a Junior Visa processing assistant will process your file once it s received in the visa office and set ready for the visa officer to process your case.
I don't know which of these is true but, in either case, I would assume that your status is updated upon receipt of your documents and, I will start preparing the documents in order not to waste much time. But again, that's a kind of gambling. There is no guarantee that CIO will approve your file. There are chances that the case may be rejected as well. So, its more wise to follow your instincts in this regard. Hope this helps.
Thank you.