I cut the slots and assembled it square. Though I will fasten it to the table when I start gluing. I don't want to induce a twist in the assemblies, what would be worse than a cup in the profile. I did a dry run in placing all the pieces in proper order, (not all pieces of wood have the same grain) and then numbered them in order of placement.
Time: 3 hrs (cutting nearly 40 pieces of wood to same size, and building a jig)