New quilt started

I've started on one of my gorgeous new kits today .... I've changed it slightly - the blocks were meant to have a tiny nine-patch in the centre but with such soft, pastel fabrics, such small fabric pieces weren't very noticeable, so I decided to just make a 3" square instead. Besides, I am lazy, and this is easier.

I need to trim my blocks and then put the sashings and borders on. I hate trimming blocks to size, but mine are always all wonky. I don't know if it is my cutting or sewing that is off, or both, but it looks like I am going to have to trim to 12 1/4" rather than 12 1/2", the intended block size. Luckily, I haven't cut my sashings or borders yet so I don't need to recut anything else to fit.