Once the joints were drawn out, I sawed all the vertical lines going with the grain. Then I used a mortise chisel to cut out the material between the two joints.
Next, I made the diagonal cuts for the dovetails and the the crosscuts to remove the remaining material. Because the legs were so thick it was tough to get the perfectly straight so I had to do quite a bit of cleanup with a chisel to get the joints good and straight.
I have cut the joinery into all four legs and begun cutting the mating joinery into the bench top. More on that next time.