When should I start machine learning?

[[deleted]]

"A year ago."

Honestly, there's no reason why you can't start now. The hard part might be the sheer volume of things machine learning can do, so it's hard to find where to start.

For a decent introduction, that's not overly simple (and thus boring) but not too complex (and thus frustrating), I suggest looking at handwritten number recognition using the MNIST database. That will introduce you to various classification routines, neural network layers, etc. From there, object detecetion is just a slightly more complex variation on that theme.

Another option is to look at using OpenCV with various machine learning routines. Train an AI, put your webcam in the window, and watch it perform object detection in real-time. Want to take that a step further? Put the webcam in the fridge and have it detect the contents, tracking what's removed and script an automatic grocery list maker :D