I also marked my sewing line on the fabric when I first started making the blocks, it really helped me get a straight line when sewing the angels. After you make a few of these you don't need to mark the fabric but when you first start out it really helps.
This is a really cute quilt block and it's worth taking the extra time to cut the small squares and make the blocks. The final size of the block is 8 1/2 x 10 1/2. Mine are a little off but I can manage that when I add the sashing between the blocks. I may even get ambitious and make the glasses to go on one of the kittens.