Originally Posted by the casual quilter

Try bringing your bobbin thread up before you start. When you are ready to FMQ, take one stitch (or use your hand wheel to put your needle through your fabric and then turn it till you bring the needle back up up). This will bring your bobbin thread to the top. Pull the bobbin thread and your needle thread under your presser foot towards the back of the machine. Then start your FMQ. That should eliminate the birds nest on the back.