When did you start testing?

My partner is really over excited and I’ve only “missed” two days of my period so far. I told him the best time to test would be after 5 days because that’s how long my period week typically lasts . Although, it is very abnormal for my period to come late, instead it usually comes 2-3 days early. Maybe that’s where his excitement is coming from. He insists on going to buy tests today, which we don’t necessarily have the money for right now. And most importantly, I don’t want a false negative and for him to be disappointed just because we tested too early. When did you guys test? If you tested early on, was it accurate? Should I? According to my glow app I was due for my period on the 5th of this month, my cycles have been 28 days long for the past 2 month and glow predicted it’d be 31 days long for this month but it hasn’t come.