Always measure - for all of the precuts I have purchased with pinked edges (which is not a lot because I try to stay away from them just for this reason)- the advertised size was from the outside of the pinked edge (the points) - so if I were to trim off the pinked edge it would not have been (lets say) a strip that is 2.5" wide.
You also have to be careful when matching up a pinked edge with a cut edge. Make sure that the points of the pinked edge line up evenly with the cut edge. When I am using pinked precuts - I randomly measure the pieces after they are sewn to make sure that I have not messed up on the seam allowance and the pieces will assemble to the correct size. Good Luck - Can not wait to see what you are making!