The tad off was in the size like it wasn't exactly 3.5" square. Lowes was willing to cut the acrylic for me but I was told that they are not that accurate. He wasn't sure if their machine needed to be calibrated or whatever the situation is. He said it is always off a little at the end of the cut. I figured I would do it on my own - it was more accurate I'm sure :)
I chose to do the 1" from the corners line as I liked the way it looked when cut. That is a personal preference. My first one I did I followed a tutorial here on QB and one of the corners was 1" and the others were 3/4 - I did it but it did look a little wonkered to me so the next one I am doing with the 1". It will make a wider pinwheel that's all.... although I haven't cut that one yet... I could change it to 3/4 and see what I think - I'll make one of each :)