When do I take a test??

So I had brown spotting that started a week ago today, and ended on Sunday. I have very irregular periods and they’re usually not regular unless I’m on birth control. I’ve been off birth control since November, and that was when my last period was so I have no idea when I could’ve ovulated or how many DPO I am. I took a test on Monday and it looked like a super faint positive but now I’m wondering if it was just an indent cuz my next 2 tests 2 days later looked negative. If the spotting I had was implantation, when should I take a test and get the most accurate result?? Thanks ladies, need all the help and hope I can get!!😕🙏🏻❤️