Honestly, I don't think having to learn some stuff before starting anything is nessecary, especially for learning a field as wide as ML/AI. It's much better to start out trying to learning something you're interested in, and then trying to fill in the gaps. This will also help you understand and motivate the underlying theory you're reading.

So for example, start with some source in ML/AI you'd like to read. If you get stuck, ask somewhere (possibly an online forum like this) what field you're having trouble with and how to get started there.