Started spotting? need some tips please

Megan • My DH & I have been together 1 1/2 yrs. I brought 3 kids & he brought 2. Just found out #6 is on it's way!!!!!!!!
So I'm guessing that my cycle was just off this month and what I thought was morning sickness must of been a stomach virus... Bummed and everything but trying to stay positive and be ready for this next cycle... So I have a few questions... 
​1. Do I count today as first day of cycle or what til there is a heavy flow?
​2. How do I go about charting bbt? I've never done this so I don't know when u start or how u do it etc.
​Any help would be great! Thanks!!!