Check out the website (I fergit so Google "square foot gardening"). That should give you enough info to get started. And you can start anytime. You just plant different stuff.
You don't really need carpentry skills either.
The trouble is...I already have a few plants in where I would wanna do the garden. So...either I'd have to start over, or I'd have to dig 'em up and hope they survived the transplant. And I'd have to get the supplies - the soil mixture and all. So it's probably something to look forward to. But...I'd like to do it eventually, for sure!