i have completed salvaging my old oak hardwood floor it ran from the front living room through a small hallway into a small bedroom.
i have glued and screwed cdx plywood to the subfloor and now it's time to install...

i have a 5inch braz cherry that i want to use as a border running the perimeter of the bedroom hallway and 2/3rds of the living room the other 1/3 rd will be tile. The borders corners will be mitered at a 45. The grid will be the oak i pulled up.

my question is will the end result be better if lay the grid first and cut the border in after or

should i lay three sides of the border fill in the oak then put the last run of the border?

i've been racking my brain for the last few weeks about how to start the install

If I understand you correctly, you want a field (grid?) of reclaimed oak flooring bordered with an apron of brazilian cherry. The b. cherry is in 5" planks. Are you planning on only one 5" row of b. cherry against the walls as your border/apron? If so, that is a tight fit for the traditional way but I do believe it shall still work. I'll ask the rest of the pros here to verify my method.
For each room, you chalk a center line the length of the room. Measure over to where you want to have the cherry border. You don't want to have little slivers of wood to meet the border so the last board in the field next to the cherry border needs to be a decent width. At least half of the regular width. If moving your center line over half the width of a field board will allow for fuller last course boards to the cherry border, then do that. The butt ends do not matter. You will run them wild and trim in place later. It is important to have the last two courses of the field floor similar in width. That's why starting in the middle is preferable. So you lay the floor starting in the middle till you get to the border. Then install a slip tongue into your starter course and reverse direction and finish the field install over to the border on the opposite side. You can either rip the last courses on the table saw to fit where the border begins OR nail in place and trim off excess with a circular saw and a fence. Either way, you need to trim the length of the field with the circular saw as you have installed it "wild" (ran it past where the border begins). Now you have the field installed, you need to rout a groove all around the perimeter with a router and easy groover bit so you can install a slip tongue that fits both the b. cherry AND the field flooring. Then cut your corner miters (test for fit) and glue and nail the b. cherry border apron, fitting the groove into the slip tongue you installed all around the field. It would also be a good idea to rout grooves into the ends of those miters and install slip tongues there as well.

gary

i appreciate you taking the time to answer my questions and point out an alternative to what i was thinking. Your way seems more simple.

nick