That could depend on the zone you live in, here in Texas grass seems to come back very quickly if all the soil is shaken off the grass back into the bed, but when I lived in Colorado I just turned the soil over and left the grass in place but turned over. Some people use roundup to kill the grass then till or just turn the soil over in place, but this requires time for the process to complete the cycle. Many here do not like using any form of chemicals to kill as they feel it causes too many other problems. Seeing as you are just starting you must live farther north. You do need to start posting your zone as others can be of a greater help when they know the zone you are gardening in as this makes a lot of difference.

YES keep the soil.

I'd hate to toss all that rich sod. Maybe consider using/renting/borrowing etc. a tiller and just till it all in together. Easier than digging by hand.

You said you wanted a 20x20 foot garden at least. Double digging a garden that size and then all the raking and smoothing and digging again? Man that's a killer and the results a only fair at best.

Hire help, hire someone with a tiller or rent a heavy duty garden tiller at least. Or build a raised bed. if you rent a tiller it needs to be rear tine not front tine and the more horse power the better.

Dave

My local hardware store has one I can rent but its front tine. Why does it have to be rear tine?

You get more weight and depth to your tilling. Makes it easier. Front tine tillers seem to kinda jump around and be way more work. Correct me if I'm wrong, I haven't tilled in many years. Nancy

Front tine tillers are much harder on the person using them, much harder to control, tend to jam up more, and don't have the weight to break new ground like rear tine tillers do. And as Nancy said they don't till as deep or as evenly so it takes 3x as long to accomplish something with them.

They are ok for use in an established garden that has already been well tilled but very poor help when making a new garden.

Dave

Better yet, don't dig at all! Make a raised bed and plant your garden.. Save your back the work..

This is what i do:

-layer newpaper/cardboard on grass
-pile soil ontop of that
-mulch
-Plant!

I used a front tine to make my garden years ago. Just go slow. A little deeper each time.