As soon as possible. A basic change in patent law has recently gone into effect, which (at risk of oversimplification) grants a patent to the first person to file, rather than the first person to invent (the old standard).
http://en.wikipedia.org/wiki/First_to_file_and_first_to_inve...
> As far as I know, the idea is unique but I don't know if I have to make it first to patent it or just patent the idea, or is the idea all that matters?
* Ideas can now be patented, so don't wait until you have a working embodiment -- by then, someone else may have patented the idea.
* You need to consult a competent patent attorney, not a public forum.
By the way, this sort of thing is very expensive.
2) Are you prepared to seek funding for, develop, test, prototype, produce, and market it with full gusto? If not, don't patent it until you are. You lose control of the clock as soon as you start the process, so you better be ready to ride the wave.