Day number two is not a big time commitment. The work involves combining the butter block and the dough. This day is integral to the light, flaky layers within the cronut.
The first 20x20 square I rolled out was not quite a square. But the second 20x20 square I rolled out was a bit more successful. The difference was the placement of the rolling pin. On the second square, I made sure that the rolling pin always overlapped the edge of the dough. (Does this make sense?) Previously when I rolled the dough there was about one inch of dough outside the end of the rolling pin, that led to edges that were not straight. The second time I made sure the rolling pin was outside the edge of dough which helped maintain the square shape. I made an infographic, below, to illustrate what I'm talking about.