I did a google search on tee shirt quilt 'images', lots of ideas. Some with sashing, some wonky, some with lots of t-shirts and some with few.
Until you know how many t-shirts are involved and how big the 'picture' is. What size would he like his quilt? Or even when the brother gets around to send them to you. I would not worry to much.
But on the other hand, it is always nice to be prepared.
