When does Glow suggest you take a test?

Ashleigh • Gave birth to my first on 2/21/15. Lincoln James. 💙
Does it suggest it based off how many days past ovulation you are? 
​Or a certain amount of days before your period? 
​Glow is suggesting I test tomorrow. I will only be 9 DPO but it's 3 days before my predicted period. I'm holding out until 11 DPO/day before AF is supposedly due. But, I was just curious what decides when Glow suggests taking a test.