I have made a stack and whack quilt with a 7-year old friend.... this is essentially the same thing.
Do what is described here. Cut all first, hopefully several at a time.
Stack them all up -- and then follow what is said here about moving pieces to the bottom. I cut, did the shuffle, and then we sewed each block one at a time and had no problem with repeating fabrics in any given block....
By the way, the 7-year-old is now in her teens and designs and sews all of her own clothes and some for her mom.... I love getting to pass this passion for fabric and sewing on!!!!