I've had the Tiramisu pattern for awhile and when I spotted this striped fabric on sale, I knew it was time.
First I did a test dress with some fabric that came in a random fabric bundle. (Quick plug time, I have no affliation with them, but I've had good results with everything I order from http://fabricmartfabrics.com/
Which turned out really well:
Basically the first time I've successfully made a wearable muslin.
For the blue striped dress, I cut out every piece individually except the pockets (oh yes, these dresses have POCKETS!). I put the center front line in the same place for the left and right front and back bodice pieces and left and right front and back skirt pieces. That isn't necessary when you work with a normal stripe because the Tiramisu pattern is designed to work with stripes (LOTS of examples from other people online), I just managed to pick the one fabric that required matching in 3 directions like a plaid.
I also shortened the skirt by about 4 inches on both dresses. Then for the blue striped dress, I had to tweak the pattern a bit to get the center front and center back seams to do what I wanted.