Check plots are printouts of the design so that they can be verified.
I printed out the schematic and both layers of the PCB layout as large as would fit on one letter sized page. Then I aligned and stapled the PCB layer plots together. I used colored pens to trace each circuit on the schematic and on the PCB layout.
In the first few minutes I found some problems. A bunch of references were not placed well, I found a section of the 3.3v net that did not get connected, and I had made a change that affected the ground plane fill that required me to redo the fill. I found these in the first half hour of verifying the check plots. I continued to make adjustments as I checked the layout.
I printed a 1:1 scale to verify the ESP-12E would fit the pads correctly and it did fit. I generated the fabrication files by clicking on plot and clicked the plot button on that dialog, then I clicked on Generate drill file and made a drill file as well. All these generated files were placed in a folder named “Fabrication” under the project directory.