Tracking your bbt

So I recently decided I would chart my bbt in the mornings. But I'm confused as to when I should. I pee. And by that I mean A LOT. I get up almost every night aroun2-4 to go pee. I've been taking it around 745 when I actually get up. But I've been reading you need to take it before you get up the first time. I go to bed at 11-12 most nights. So it varies to when I have to get up to go pee. Currently my temp has been raised 98.3 everyday at 745. No dips. I'm taking a test tomorrow.