That is an exciting project. I'd also just cut out my blocks, whatever size you decide and then let the blocks tell you how to arrange them.That is the most pleasing arrangement using the fabrics you have. You may want to supplement with other fabrics depending how much clothing you have on hand and size of the quilts. I wouldn't worry about shrinkage if these clothes were washed and worn, but would try to stay on straight of grain as much as possible to keep your blocks from stretching out of place too much. I am excited for you! Good luck on your new project. :D

Welcome, welcome, welcome......What a great project you have planned! Birth of my first grandchild got me into making quilts. Once that first crib sized quilt was done, I was hooked. I echo everyone's advice, though, to practice cutting with that rotary cutter on lots of "junk" fabric before starting the quilt. Good luck! :lol: