I don't starch very often. When I do it is cause the fabric is kinda wimpy and I am sewing some pointy triangles. If I have lots to do, I'd lay down some scrap pressing sheet on the ironing board first, just so it doesn't get all scuzzy. then I'd lay lot's of pieces down close together cause that spray goes everywhere. then like the others suggested spray and let set till foam goes away and press up and down to dry. Move when cool.
I don't usually spray yardage, but I will decide to spray after I cut strips - occasionally.