adding borders...question?
 

I finally have this quilt done to the point of adding the borders. All four edges have 9-patches, on point, that will have to be trimmed. My question is do I trim them first, then add borders? Or mark the lines and sew down the first border and then trim? Which is easiest? This pic is before I fixed the orientation of a couple of 9-patches...LOL.

Having never done exactly what you're doing, I can't give you an answer based on experience.
Doubt it would make much difference either way, as long as your seam is straight.
Looks good to me!

I have never done anything quite like that, but just looking at it, I think I would have to trim first.

I prefer to sew two matching edges together. If I were sewing that, I would trim my quilt to square before sewing on the border.

I would trim first so that your intersections in the 9 patch blocks and setting triangles are easier to match to your 1/4 seam when you sew on the borders.

Because trimming the 9-patch blocks will leave you with bias edges (I don't know whether some of your setting triangles might also be this way), you might want to stabilize the edges with this trick first. You can buy the twill tape at chain fabric stores in the section with rick rack, seam binding, and hem tape.

Jan in VA

I suggest that you trim first. It is easier to get even straight line with 1/4" seam allowance. Also it should be easier to trim excess fabric. by using ruler to trim to 1/4" seam it will allow you to see if points line up and if you need to resew.

I think I would also trim first - even if that exposes bias edges. You can stabilize them by stay stitching or tape as others have said. I think you would want to get the top nice and square before you add the borders.

When I added the borders to the french braid, I marked the edge 1/4" out from the finished seam location and matched up the border to that, sewed it, then trimmed it. I think it's a bit more stable that way. Starch helps!