Early then late

Kate • Thu, Aug 11

I was 4 days early last month and due on Monday, however now on day 28 and no sign yet! I had some dark brown spotting 5 days after my last period but this is too early for me implantation bleed so didn't think anything of it! I am usually 25/26 days like clockwork. I have been early a few time on day 23 but never late! Is this a sign?