Stupid question, but what is the purpose of "blocking" a quilt? It looks like the quilt is already quilted right? Why not just bind it and be done? Why does it have to be stretched out to a certain size?
It's a stunning quilt!
(also, would washing the batting as well as the fabric help?)

Using poly batting and prewashing fabric will make the quilt not shrink. But the "look" of cotton batting after it's shrunk a bit can add charm to certain types of designs. I use the poly batting if I don't want shrinkage and to keep it flat looking-for the more modern types of quilts. I have to say, that when the quilt shrinks up with cotton batting, it tends to hide many boo-boos and not quite in the ditch stitching. So that's a good thing.

I'm so new, I don't have a comment about blocking. But wanted to say, What a lovely quilt! Blessings

The purpose of blocking is to make a quilt flat and square, primarily for show and hanging, so that it doesn't have ripples and distortions and hangs straight. Personally, I don't see much need for blocking if it's going on a bed.

That's a good idea to mark the foam board.

I block the quilt after is quilted but before is binded. I don't have to do it again, as it keeps the shape well.

I've made over 150 quilts and never blocked one of them.
YTQ

Love the quilt!!!

I can't help you with the blocking but that quilt is beautiful. Great job and good luck on getting it square. Great quilt.

nice

Wow, love the quilt! Good luck on blocking it!