I need advice ASAP!

Okay, so, here's the problem... I'm 3 days late on my period. I know, it may sound stupid, but I am a little worried. Is it too soon to take a pregnancy test? Or should I wait longer? I've always had very irregular periods, usually going months without periods, but within the last year or so they've become more regular, and usually occur at the same time every month. This is my first month on eve, and maybe seeing the calendar say I was supposed to start three days ago has me more on edge than ever, but I need advice! Please, no negative or rude comments, I'm sure anyone on here in my position would be slightly worried too.