Confused when to test

I have a FRER, it says 6 days sooner (than a period, right?) which according to Glow is 2/26. So I started testing 2/20. However, then I looked at highest dates of implantation and it was yesterday 2/21 and I read to wait a couple days after that to test for the hcg to get high enough. I did have cramping yesterday too, So which way is it? Is it too early or not? First day LMP 1/31 for 5 days.