[dagw]

What is your interest in deep learning? Developing new and novel algorithms, or applying already existing algorithms to new and novel problems, domains and datasets? If it's the latter then high level math skills aren't that necessary.

A solid understanding of the domain and data under investigation is much more important, as is being a decent programmer, knowing your way around data cleaning and data management and having a solid understanding the strengths and weaknesses of the different algorithms out there.

If you're interested the absolute best way to get started is just to start. Download a well studied data set like this one: http://yann.lecun.com/exdb/mnist/ Grab one of the dozens of tutorials that talk about how to approach this data set and follow along in something like scikit-learn or Flux.jl. You'll soon enough have gone from zero to having developed a tool that can recognize handwritten digits. From there you can just keep going.