when to test?

Autumn • My beautiful son born 5/26/19 💙🥰❤️😍
Don't want another negative. I have a habit of testing even if my period is an hour late, and then usually get my period the next day. 
My period is four days late which is unusual for me because my period comes same time every month with me being on vitex. 
When should I test? Don't want another negative