When to test

Becca • I`m 19 and ttc with my fiancé of 4 years :) just want our own little family
I've worked out I would be 3 weeks pregnant I'm unsure not getting my hopes up been having some symptoms I was sick the other day very nauseus tired back ache and recently sore breasts and a few cramps just uncertain, AF should be here weekend but I never have any symptoms before AF comes, also I went 2 get my palms read and she said soon I will rock the cradel and in 3 weeks I will get good news that will change my life and on Sunday the 30th will be two weeks so trying to hold of testing until the day I get good news, anyway back to the point when should I test???