So accurate is my BBT?

So I know you should take your bbt at the same time every morning, and after a good night's rest, but that's just not working for me! I've been logging it, but sat back this morning and realized I can't do that! I know you should sleep for at least 3 hours before taking it, but I can count on having to get up every weekday morning at 6 to 6:30 a.m. to pee, and my alarm goes off at 7:45! Then on weekends, of course I can sleep through the whole night, but don't always remember to take it! Smh, what should I do?