After you've selected the file you want to engrave, draw a vector box around the design and run ONLY that job. Make sure the red dot pointer is on and the lid is open, so the laser won't fire. This will help ensure your design is engraved exactly where you want it.
When you're happy with the placement of the design, remove the vector box and send the job to the laser.
After the engraving is finished, take the apron out of the machine and remove the scrap material and the project is complete.