The best I can suggest it what I do. To allow for minor wood changes after machining I shoot for .005 to .010 on both the outside and inside areas. In a perfect world it would be best to do it as close as possible but that might not be the best move. If you have wood shrink slightly after machining you will be very happy to have this extra wood.
After machining I let the wood rest for a month or more to allow the stresses in the wood which machining can cause and can release to become stable. Then finish inletting the wood. A small amount of wood left by .005 or .010 can be easily removed by sharp tools.
How long have you had your wood? Is it dry? Is it stable? There is a difference. Where have you stored your wood? Do not use wood that is not both dry and stable. My wood rack has wood that has been drying for years. Any wood I have in my rack seasoned for less than four years is not ready to use in my opinion. Most blanks I have have been drying and seasoning for 10 plus years.
The hardest thing to be is patient when you get near the end of a project. Using wood not ready to be used will ruin the job. Many years ago I inletted a blank that was not fully dry and stable. Bought it as dry and tested the moisture content. Looked OK. It was not totally dry and stable. I watched it shrink and twist over the next two years. Real bad things and words came out of my mouth. Be patient.
