I generally use starch on fabric that needs it before I cut the fabric-so, fabric is already starched when blocks are done. I steam (IF) steam is necessary... Most of the time a dry iron is all that is necessary to get my blocks to lay flat, especially large blocks like turning twenties. I press as I go constructing blocks so I seldom need to do any*squaring up,* if I do need to square up a block when it is constructed I just lay it on my cutting table, place my ruler, trim side &top, turn 180°, trim side & top again then no more pressing is needed until I am constructing rows (pressing seams) too much pressing -- especially with steam and/or starch leads to distorted blocks. Pressing should be kept to a minimum and when necessary. If your fabrics have been ironed (and perhaps starched) before you make your first cuts and you sew straight often simply finger pressing is all you need to do while making blocks. Then a good press on each block before constructing rows.