Hmm...period issue

So I always start 2 days early on my period. Every cycle. This month. It says in supposed to start on the 17th. But I always start 2 days early. Haven't got my period yet. And today I haven't started. Is it possible that I could have received? I'm constantly having heartburn. My lower back is aching. And my nipples area little sensitive. Should I take a test today? Or wait until tomorrow?