Couple of suggestions since this is your first build:
1. Since you are building one of Nick's boats, I would advise rigorously following the build sequence in his book.
2. I would suggest re-reading chapter 5 where he talks about form mounting/spacing.
3. What Justin was trying to tell you is that the holes in your forms look very much too big for the size of your strong back. Are the holes in the forms 2"x4"? Is the strongback a true 2"x4"? I built two strip boats following Nick's book and the forms should fit very tightly on the strongback. With as much slop as you have in the picture you will have to be very careful aligning the forms and then lock them tightly in place prior to starting to strip. One form just 1/4" out of alignment will result in a noticeable bump in your boat. I pict or my first below: