I do a modified quilt as you go.
1. complete all your blocks and sew them together in thirds. I do mine in columns.
2. sandwich 1/3 of the top with batting 3 inches wider on the left and right. (or more on the left depending on the boarder)
3. sandwich the entire back, lining up the left side even with the batting.
4. Quilt that section how ever you want.
5. Attach another section of batting to the previous batting, making sure that the top or the backing is not in the way.
6. place the next section of the top face down on the previous top section and using a 1/4 inch seam.
7. Sandwich that section together and proceed with the next quilting.
8. Attach the 3rd section like you did the 2nd section.
9. I attach the boarders either before or after the quilting depending on what look I am trying to get.
I have done all my quilts that are bigger than a twin size.