When to take a test??

Hannah

So if we did conceive this month how would I calculate how far along I would be and when should I take a test?? I’m not sure if I should count from the very first day I started my period or the second time I started. The second time was light bleeding and I’m pretty sure I was fertile the 17th and 18th also because I had ovulation discharge but not sure if it counts because it had a little bit of blood in it.