The American nuke powered Virginia class sub started construction in 1999 and will be ready NOT before 2015. That's >15 years from design to operationalization. The cost? $2.5 billion!
The British Astute class nuke sub will take 14 years. The cost? $2.1 billion.
Both nations have decades of experience in construction of subs and naval warships. Even then it is taking them 14-15 years for design and construction of new subs costing a couple of billion dollars each!
So all this talk of designing, constructing, testing and operationalizing a nuke sub by Pakistan in 5-6 years is a pipe dream unless they borrow and assemble the older generation systems of the Chinese nuclear subs.
In short, it's designs, parts and assemblies from old Chinese nuke subs and cash for construction from Pakistan's eternal benefactors, the US of A!
And needless to say, the construction proper is going to be done in Chinese shipyards with Chinese expertise and Chinese workers.
So how is it going to be a 'Pakistani' nuclear sub??