When you make your bom squares and if they haven't been prewashed, would you prewash your boarder fabric before you cut it?

I'm not a big prewasher, so I probably wouldn't.

I'd wait until the whole quilt was done & wash it then. JMHO!!!

ditto

only if worried about color running, if it is stable, i would wash the whole quilt together, if you wash the borders separatly they are not going to 'shrink' evenly with the rest of the fabrics used.

Nope, wait and wash when it's finished.

I either prewash it all or none :D:D:D

I agree!

I'm with amma - all or none. That way everything can shrink/adjust the same.

I would not. I would finish the quilt and then wash it all at once.