Question

My husband and I just started TTC. We had sex on Sunday which was my second to last "fertile day". I also had fertile CM that day and the next. Today I was nauseous all morning and still am a bit as well as I noticed breast tenderness. Of course my mind is going crazy. But these symptoms don't start this early on right? Also when is the earliest I can take a pregnancy test? My cycle is very regular 28 days to the tee pretty much. My period would normally start the 26th.