Eric;
Just browsing through these threads and ran across yours. When we moved out of the city I still (needed, had to ) wanted to garden, but after testing I found I had hardpan clay which would be difficult for my favorite root crops, and since my back yard is just a shade under 2 acres, I decided to try quite a few techniques I hadn't before: double digging one of them. IMO it's a very effective method to break up (and in) soil for a new garden. My oldest beds are about 3 or 4 years old and they are the best place for your prized veggies (Whatever they may be). I've read that they must be re-done every few years or so, but so far all I've done is mulch with finely chopped fall leaves and turn them into the soil in the spring, it seems to be keeping the soil in good to GREAT condition. A good heavy duty broadfork will help in maintaining your beds - my choice would be Meadow Creature.
Hope this helps.
J.R.
P.S. Sorry but I forgot your second question. The best time to do this is now, it's kinda like that old Chinese proverb about the best time to plant a tree.