Is this accurate?

What do you ladies think? I have brown spotting on the 29th. I am assuming it is implantation bleesing since I only had it once when I wiped. According to this I need to wait until Sat or Sun to test to get a positive. Do you agree? I have already taken two tests and they were negative but if I didn’t have implantation until yesterday the hcg would still be really low. Thoughts??