Congratulations on getting your quilt made, by the way! :)
Does your machine have a drop in bobbin (lies horizontally in the case) or a vertical bobbin? (stands up on end in the bobbin case)
Do you have a practice sandwich for testing your stitching? I just use two pieces of muslin with a piece of batt in between. Lets me test the tensions, designs, etc, without committing them to the quilt.
Practice on your sandwich and get all the quirks ironed out before taking it to the quilt. :)
Thread your machine with the presser foot UP, so that the thread can get all the way in between the tension disks, but don't forget to lower the presser foot before you actually start sewing. The way this foot is made, it can look like it's lowered when it really isn't. There isn't such an obvious reminder there to put it down.
Big loops and nests on the underside almost always indicate that there is not enough tension on the needle thread.
This can be from not lowering the presser foot, from not threading the machine with the presser foot up, from a piece of debris between the disks that is preventing their clamping onto the thread, etc. Something is preventing there being enough tension on the needle thread. :)