Basal = lowest or Basal = first?

Sarah

I read that bbt is the lowest temperature during the day, but that you should always record it when you wake-up, before expending any energy.

Well, when I woke-up, my temp was 98.8. Then, a bit later, I put on a sweatshirt and took a nap. I took it again after I woke-up from the nap and itbwas 98.4.

So, my recorded bbt should be 98.4, right?