How quick to test?

Allison • TTC #1 through IVF (or a miracle naturally)
I was supposed to start my period today and it didn't come. So I took a pregnancy test and it came back positive! But was it too soon to test? I only ask because my husband and I only have a 1% chance of conceiving naturally, and I am in complete shock and don't really know what to do. Can this really be true?