With the L bracket secure, I put down the cutter and adjust the blade to the outside of the part. Hard to see in this photo, you will need to make sure you have good lighting when working with parts this small.
Again, lightly placing the cutter on the paper while adjusting the position of the blade, then lock it down.
With the blade locked in position, I did a test cut on some scrap paper to make sure the circle is the right size.
The test cut looks good, so lets cut the actual part.
Success! I have a perfectly cut 2.5 MM part.