The only hardware for the shelf are the 2 brackets that mount to the back of the supports. They will be screwed in after I cut mortices to hold them. It is funny to me that I used more tools installing the brackets that I have used up to this point in the project. Here is everything that I used.
Use the hardware to knife the outside edges of the mortise. I used a wheel gage, but just the knife and a steady hand would do fine. Next use a chisel to cut some relief in the waste area.
I went side to side since my chisel was not as wide as the mortise. As far as chisel depth, just guess. The mortice needs to be deep enough to cover the bracket and flat. The exact depth does not matter since I can easily adjust the screws going in the wall for depth of the bracket. After making the relife cuts, use your chisel and mallet to finish the mortise. Try to get the bottom pretty flat. Test fit with the bracket occasionally and use a careful hand. No router plane needed, you can see flat. This step should be easy after the hand cut dadoes.
Once the bracket sits flat inside the mortise, mark the holes using the bracket as a guide. Here I have marked the center of holes to be drilled. I marked the center of the holes with an awl to ensure that the drill started in the right place. I picked up this tip from Christopher Schwarz and my holes have been on target ever since I started adding this little step. The 3 regular holes are for screws to hold the brackets, the elongated holes are relief for the screw heads that will be sticking out of the wall. The size of the relief holes is not critical, just bigger than the screw heads.
Here the relief holes are drilled and I am ready to drill the holes for the mounting screws. Note, the screws that came with the brackets were pretty small. I used 1 1/2in screws for the top screw and 1in screws for the bottom 2. The top screw should bear most of the load and these longer screws made me feel better.