The good:-thanks all for the suggestions 1- straight edge and circular works great for cutting to size.
The bad: 2- miter on my TS doesn't work well for cutting length down to size.
What I did: I'm in the process making a cross-cut sled with the dimensions of about 18" x 30" using both miter slots in TS table. So the question is, is there a way to check the calibration of the sled I made. If I cut a straight piece of scrap and then flip it over and cut again, and then measure the width. If they are the same over the full length... does that mean I'm square?