Sooo confused CD 40!!! BFN and no AF!


So my periods are always pretty regular between 29-34 days. I am currently on cycle day 40 with no period and no positive test. I’ve never been late on my period and am usually a day early. I tested yesterday and got a BFN. How long should I wait to test again or start getting concerned? Just confused since this has never happened before so not sure if I just wait forever lol.