You really want to cut those charm squares into 2.5" squares and quarter one on the diagonal to make HSTs? Those are tiny and the finished size of each 4 patch would be 4" and the same for the hourglass block, that is if you keep a consistent 1/4" seam.

I figure maybe you were thinking to sew 4 charms together to get her 4 patch, which works, but there's no way you can get a layer cake sized hourglass block out of charms.