How late do you let your period be before testing?

Alli • Grace 10-8-18 ❤️❤️

How late do you let your period be before testing? Mine was supposed to start today and hasn’t yet! I want to test on my day off (Wednesday, so 2 days from now) because if I am, I can get something together to surprise my husband with when he gets home! But I’m not sure if I should wait a bit longer?