Joining Blocks:
In taking the blocks off the design wall, do them row by row and place a piece of masking tape on the beginning block of each row with its appropriate row number. You can see how I've done that in these pics. Lay a single row out and sew them together while keeping them in order at the same time. Then join the rows together.
Next is a pic of all the blocks stacked neatly and numbered ready for sewing! Then the following pic shows a close up so you can see the block with masking tape marked #3 on the block for easy identification and keeping it all in order! lol.