Quant firms do hire from Waterloo. If you have $$$$$$ to spend, you might be interested in top need aware schools like UChicago and Cornell. To develop your math skills, check out the art of problem solving books, alcumus, mathdash, and Courseware | University of Waterloo - CEMC (this last tool let’s you generate problems by difficulty (A, B, C), grade level, and subject/topic so you can focus on problems that are just right in difficulty)
For competitive programming, check out USACO.guide