Prepare the Grommet Area
Use a hot iron to press the back panel flat, so you can cleanly find the back edge.
I like to re-enforce my grommets with twill tape, which is secured by the boning channel stitches. The twill tape is 1″ wide. I usually feed it through Panel 1 using a Sharpie pen. I’m sure a proper bodkin will work great too. ;)
Make sure the twill tape is flat within the panel, and close to the back edge of the corset so it will catch in the seams.
Again, I use the presser foot as my guide for the channel width, using my hands to keep the back panel flat to the fold.
I usually make my grommet channel 5/8″ wide, which is just larger than the size #0 grommets I typically use. When I plan to use #00 grommets, I make the channel 1/2″ wide.
When I need to stitch at a depth greater than the marks on my sewing machine plate (as often happens), I typically use Sharpie to mark a seam guide. It dries quickly, and can be easily cleaned off of metal and most plastics with a little rubbing alcohol.
An alternative is to place a piece of masking tape on your machine and mark the tape in pencil or normal pen.
I again use the presser foot to guide the width of the last boning channel.