On my first guitar, I glued the braces on first, and then cut the center strip into five sections, and glued it in-between the braces. The center strip didn't wind up being in exactly a straight line as a result.
On this guitar I thought I'd try gluing the center strip down, and then chisel out four sections for the braces to go thru.
Here's the center strip being glued down. I use popsicle sticks so my go bars don't dent the wooden parts. The back is resting on a 2"x2" that has a 15' radius cut into it, which matches the radius of the braces, so that the back will be arched.
And here is the center strip glued down. The edges of the center strip have been rounded. Gives it a more finished look. I did that with a piece of sandpaper glued to a little wood block.
Since I only have one 2"x2" with the back radius cut into it, I glue down the braces one at a time.
Here are all the back braces glued on.
Here's detail of the bracing that will show thru the soundhole.