Thanks for the references......

I spoke with the installer at the place I bought the wood and
recommends exactly the opposite! I.e. put the border in first. He says
that, yes, when you reach the far side, the angles may not be exactly
90 degrees but its easier to cut 89 degrees on the miter saw than to
get the "field" centered and true and them put in the border.

He also says, you can make both ways work.

Not sure what I'll do -- I'll have to decide tomorrow.