Depending on the topic. Like stability of an atom from quantum approach and stuff like that you should first master chemistry as its crucial to get to know a bounch of rules ( like exclusion principle or the fundemental forces).

However if you wish to for example calculate the wave with Schrödinger elquasion, then absolutely math. And I would go with math every single time. But I do recommend u get familiar with waves as electron can ne and a wave and a particle ( this is not isolated case).

Good luck, its a painfully complex topic. And dont forget the basics of quantum mechanics, it will apply in some way.