You are wrong in this Yusuf, What is of paramount importance to PRC and Pakistan, much more than Mumbai (not Delhi) is to stop India's nuclear launches, and they still have some left for Mumbai, Bangalore etc.
It is not mobile missle site's (which only comes active after mating)they will be targeting, rather Nuclear Weapon storage sites and missile site's, which are both separate. Especially, like you say, we assemble after we get the first strike, then all the chinese have to do is take away the Nuclear Storage houses or Missile sites. There goes our second strike, I do agree, they cant take all our sites down, they wont have the intel for that. But they can severely degrade our capability to strike back, giving much chance to their ABM.
There it is important we have overwhelming nuclear advantage, and we have missile's ready to be mated at the first sign of real trouble. We might need to have a warning system similar to the Defcon in the US.