I can't help but think that misting and stretching with the iron won't last. Once the fabric cools, dries and relaxes, it will return to it's natural size.
I can't get the proper size if I sew full 1/4" seams. I sew scant quarter inch and use the magnetic seam guide to ensure I don't sew wider. That usually gives me a teeny bit to sliver trim around the blocks. Or not. Sometimes they just come out the right size by sewing the scant quarter.
My Juki has a scant quarter inch foot that makes it really easy to follow. On my old Bernina, I have to move the needle one click to the right to get the scant quarter. Both work well.