I have to believe that the "more likely to use them" is offset (I hope entirely) by the taboo of deciding to do so. If deciding to use a nuclear weapon is an open invitation for retaliation in kind, then you would expect the established players in the nuclear power game to shut it down with extreme prejudice for exactly that reason.
A smaller opening volley doesn't feel like any increased incentive to initiate said volley.
It's assured destruction. The degree and ferocity of the conventional military response to any state which opens with a small scale nuclear attack would be unlike any wars to date.
You do it and you'll get to watch the US, China and Russia briefly join forces and annihilate your infrastructure with extreme prejudice - with options to use their arsenals if anyone suspects you'll try to while this is happening.
A smaller opening volley doesn't feel like any increased incentive to initiate said volley.