I have just completed my first quilt top that I did from a pattern. It is close to square, but not quite--it does lay flat--I think. It's a lap quilt, about 54.5" x 59". When I measure it in several places, it can be as much as a 3/8" variation in the length (the width is closer to exact). My question is--should I trim it now, before I baste it, quilt it and bind it, or should I wait until after it's quilted before I work on squaring it? How much leeway do I have with the quilt top? How close to perfect does it have to be before it's sandwiched?