Need a little advice on Flannel for backing

I am done......put a fork in me! I have been sewing: a custom tote bag with monogram, and bumper pads and crib skirt the past week. The fabric for said bumper pads and crib skirt was $30 plus a yard. Yikes! I though $10 a yard for quilt fabric was expensive.It was hard making that first cut worrying that I would mess things up. Glad to be back to quilting!

I need a little help with using flannel as a backing and batting both. I will not be using any batting, just the flannel as a backing. I did not prewash any of the fabric in the quilt top, but want to know if I should at least wash the flannel once before I use it. I think that I read that flannel shrinks more than cotton. I don't want it to mess up the top if it shrinks a lot more. Does anyone who has used flannel as backing have any advice? Thank you in advance.

BTW, JoAnn's has flannel for 1/2 price right now.....really cute prints.

I made a sock monkey with a pair of Target's dollar socks. It was so much fun to make. Pictures coming soon.

Take care,
Cathy