Are you doing this as a quilt as you go? Quick and easy.
1. Cut out batting and a backing colour same size as front
2. Start at the step side left at the top.
3. Place first piece bottom batting top as if a sandwich . Place top of next piece right sides together .
4. Place batting on top of the second top.
5. Place back piece right side to right side of first piec.
6' machine all together I would use 1/2incg seam .
7. Press well.
I am sure you get the idea it does grow vey quickly and you can trim seam if you wish.
You can also quilt a design on each section when sewn