If you decide to turn the soil over, I'd at least wait until cooler weather gets here to either dig it up or till it if you don't plan to plant until spring. I like to remove the sod after tilling a new patch of soil to help keep it from re-establishing in the freshly tilled soil.
You can then cover the area you tilled with layers of cardboard, newspaper, grass clippings, leaves, etc. and that will keep weeds down and the organic matter will decompose over time adding nutrients to the soil.
Before planting anything, I'd recommend taking some soil samples and having your state agricultural service do a soil test. It is done for a nominal fee and it will tell you the condition of your soil and what, if anything, needs to be added.
You can start now to start a nice compost pile so it will be ready by spring. There is a compost site on the forum with all the info you need to get started.