I did two like this. Measure each decal/design, deduct 1 inch vertical and horizontal (for seam allowance) and mark on graph paper where you want in (using each square as one inch). I allowed a 2 inch spacing (minimum) between each design piece. When the whole thing is on the graph paper, you're ready to cut fabric but don't forget to add seam allowance to each fabric piece. there will be lots of Y seams as you go along.

Graph paper is my best friend when I make Tee shirt quilts. I can see 9 or 10 sections or blocks in this pattern, I have made one kinda like this. That is where the graph paper come to play. You can do a mock and move things around easy. Please get money in advance for supplies. The last quilt I made I sent the finished quilt with the supply cost, clearly written. Then payment for work was written at the bottom of the invoice. I did get supply money, but the payment for work done would not have gotten me a value meal at Burger King. The lady thought I worked for free. But she and her daughter loved the quilt. I had to ask her not to say a word about what she paid me to do this quilt. From now on I will stated money up front supplies plus $$$ for work. This was a lesson well learned.