I agree with those who suggest pulling your threads tight before you make those first few stitches. Mine makes the exact looking mess if I forget to do that. Even though the knots are on the bobbin thread side, in my case, it is actually the top thread that has pulled down and knotted up, as I learned from ripping them out. LOL
The best solution I have found is the use of leaders and enders.... either small scraps or pieces from another project that you can sew at the beginning and end of each stitching session.
When these won't work, then holding that top thread tight does the trick for me. Good luck!