It's unusual to O so early but not unheard of. Also, you may find your body is gearing up to O but won't until later, my body does this a lot, it's related to my PCOS but it can happen to people without PCOS as well. The hormones start which gives me a pos O test but the temps don't rise. The only way for me to know if I have O'd is the temp rise.

Graphs can vary a lot month to month, temps can be dependant on a lot of different things so each month may look different, what's important is the pattern of this graph and it does look like a temp dip, similar to what you'd see pre- O. Sorry to say but te only way to know for sure is to see what happens with your temp over the next few days. Hopefully your body will hold off for a few days so your DF will be happy to BD.