I used to think this too but now I prefer the idea of J-35 vs a larger India previous generation force to be balanced. In other words; J-35 can balance a numerical superiority, but technically inferior force. This allows smaller countries to have balance with larger ones.J-35 to Pakistan would expedite India's acquisition of 5th generation fighters, which actually makes things more complicated for both China and Pakistan. Currently, a few squadron of J-10C is enough for the entire IAF to stand down. If IAF were to fast track acquisition of either Su-57 or even F-35, then China would also need to deploy J-20/J-35 to WTC. The strategic decision is to delay J-35 to Pakistan for as long as possible.
I don’t think F-35 is available for India, and even if it in the future, then the best time for Pakistan to get the J-35 is actually now, not then.
The other thing is, and this is not often mentioned, is that India is not the only serious security threat to Pakistan, the US is also.
The J-35 isn’t designed to keep India at bay, but the USA.