Scared I might be pregnant😓

My SO and I had sex on the 11th. We didn't use any protection, but he did pull out (I know. It's not an effective method). Today I've been lightly bleeding, which I believe to be implantation bleeding because my period isn't due for another 5 days. I've also been having lower stomach cramps all day. I'm scared that I'm pregnant. When should I take a home test just to be sure?