I don't think so. China should always keep a tight mum on the exact size of her nuclear arsenal.
Just like what
@FairAndUnbiased said,
the card can only be used once. So China would need to use her cards very, very wisely.
In my opinion, the only time that China should even consider using this card would be to push for
brinkmanship against the US, her allies and Taiwan (or vice-versa) regarding Taiwan's reunification issue. For example, in case the US and her allies threaten to directly intervene in China's military operation to reunify Taiwan.
But even if such
brinkmanship is used, China should
never reveal the true size of her nuclear arsenal. Instead of the usual:
"China's nuclear arsenal is enough to ensure minimum level of strategic deterrence";
China could go with
leaks-like "statements" from ambiguous sources, such as:
"China's nuclear arsenal is capable of the total destruction of the populace of all the XXX/offending countries"; or
"China's nuclear arsenal is sufficient to wipe out all military sites and population centers of all the XXX/offending countries"; or
"China's nuclear arsenal is viable in ensuring that all the XXX/offending countries would never possess the capability of harming the nation of China and the Chinese people, forever"; or
"China's nuclear arsenal is enough to ensure that all the XXX/offending countries would never have the ability to even rebuilt/reconstruct themselves to become a functional part of the global society, ever again"; etc.
Of course the last one sounds extreme, but what can you do when you are left with no other choices?
In short, keeping the enemy guessing about China's true nuclear strike capabilities would be the best way to keep the enemy at bay. There's no need to reveal your best cards, when your currently available just-okay cards work just fine.