Having done this once, I would recommend you find a concrete finishing outfit and watch them do the job while you sip a cold adult beverage. You wouldn't believe how heavy concrete is when you're on the working end of a shovel. And, if you want it anywhere near level, smooth, etc., you've got to know what you're doing and have the right tools. It does a lousy job of leveling itself, as hj pointed out.
But, to answer your question, I watched an experienced crew of 3 do a similar job in just under an hour. One of them mostly supervised, and the concrete was pumped, rather than wheeled. I'd add another guy if you don't want to pay for the pump.