BBT this morning

Emilie
I'm projected to start AF tomorrow. I've been taking my temp every morning. It spiked about four days ago and has been at that degree for those four days. But this morning it went down .4 degrees. It was 98.1, now it's 97.7. People have said it will go down a day or two before AF? Is the temp decrease significant enough to know that AF will be here soon?