Nauseous

Ok so my af is due in 6 days the past two days I have been nauseous on and off ! Could this be a sign of my period starting soon or pregnancy ? I had an early miscarriage on July 9 had my last period on August 7 my cycle is usually 25 days so second question when is the earliest I should take a test I wanna take one now but I know it's too early 😓 so when should I take one