Szarka Istvan - Start now, don’t wait. Heck, if you had dev or scripting experience I would point you at PowerShell in Action 2nd Edition, still my favorite PowerShell book.
If you start learning with an older version (2 or later), you will be fine - what you learn almost always carries forward. Go for ps in a month of lunches 3, it will be helpful!
If you start learning with the newer versions, you should be aware that if you rely on newer language features or commands, they will break compatibility on systems running PowerShell version 2. For example, I love the new [pscustomobject] type accelerator, but I have to force myself to not use it because I generally target PS2 and later systems (it won’t work in PS2).