Jenny suggests doing small projects with this method. Just choose the size you want to make, crib looks to be the best size. I would not use fleese for the backing, its polyester and will shrink differently than your cottons.
This is not made with a jellyroll, she cut different width strips for this project.
I have done this quilt as you go but made blocks/rows, and quilted as I went for each row,
and came back later and stitched between the rows. A great idea for a quick gift or charity quilts.