Measure the normal waist size (on your bare skin) and then the waist measurement around your laced corset.
S5.1 How far (inch or cm) did the corset narrows your waist?
S5.2 What is the material of your new corset (plain fabric, satin, velvet, leather, vinyl, latex, ..)?
S5.3 How many buttons of your blouse were closed when you finished the tour.