Here's how I do it.
I tape newspaper together to get a large square the "size" of the tablecloth I want to make. Than I fold in 4ths to find the center, unfold and lay on the floor. (May need the help of someone limber!) Take a pencil and string, make the string 1/2 the length of the finished tablecloth, tie string to pencil, hold string down on the center mark and draw your circle. Cut our and use for pattern remember to allow for hems, etc. :D :D
Oops, just reread your post!! LOL. Quilt huh, You can piece squares together until you have your square?? Than cut your circle.
I'm sure there are other, better replies coming!!