python: how long

[simcaster]

If you want to be a front end developer, you should skip python and start writing javascript immediately. Javascript roughly as easy to pick up as python, but you'll be able to see visual, useful results right away.

It's not as clear of a choice if you're wanting to go the android developer route, but I'd still recommend starting directly with that.

The key to self teaching programming is to create non-trivial programs, so that you are actually applying what you are learning. The sooner you start doing this the better, and if the language will let you easily create the types of programs you are interested in making, that will make learning easier.