4 days late

So I am 21 years old. I am four days late going on 5 by both of my apps and no symptoms of AF my periods are very very regular average cycle is 31 days. Last month it was 35 and I’m on day 35 now. When should I test? Not trying to get my hopes up or anything. It’s just weird that my cycle was like this last month so I’m kinda thinking no.