When to test

I am 2 days late on my period according to this app my period is always on time. I'm having really light brown discharge almost like a tan or beige color im not sure if that's the start of my period or if i could be pregnant. I purposely had sex before, during and after ovulation. I work midnights so the early morning testing doesn't sound like it will be accurate. And I don't sleep a whole 8 hrs during the day. So when exactly should I test ?