Bbt chart dip .. Help?

Brandi-lea • Khaleesi-May Dizney Van Vliet - my precious daughter born on 23.6.15 👶🏼🌸
Hello everyone :) so, I took my temp today at 9am and it was lower than my coverline! 
​I'm totally freaking out because I'm only 4dpo and AF definitely shouldn't arrive yet! 
​If anything, in my hole life I've never been more than 2 days early, so if AF comes knocking that's definitely not normal for me! 
​Does anyone have any idea what's going on? I'm only 4dpo so I wouldn't say it's and implantation dip.. I'm just forsaking out! Thank you in advance for any comments :)