When to test

I am supposed to start my Period on November 1st, that would be 28 days since the start of my last period. I’m pretty regular. I have had horrible stomach aches, not sure if it’s from what I’ve been eating or pregnancy symptoms. When can I take an early response pregnancy test? Should I wait the 6 days before my missed period? Every month when I take a test it always comes up negative and then I get my period the next day. I hate wasting money on test, but I am just so anxious. I’ve never actually bought the 6 days before missed period test and wasn’t sure if they worked well enough or not