Of course, your router is unplugged right, especially while measuring and marking around the bit.
Using "Tee-Square" to accurately find edge of cove bit and mark table in both directions.
Marking both outside edges of the router bit in both directions gives you a way to find exact center.
Flute halves will line up great after doing this, and it just takes a minute or two.
Just another view, hope you're geting how easy this is.
Marking this front to back on table gives you the start and stop routing points.
Just another view. I use black pencil for the outer edges.
Fine 'Sharpie' marker works great too.
When I use Sharpie I just make short scribe marks.
After you get the outer edges marked use another color (blue) to mark center-line
Doing this precisely, at least once, makes for a really nice glue-up.
Using "Tee-Square" to mark center-line across table.
Completed router table layout.
Setting fence to equal half the width of your flute blank.