Hey ladiesss

So I’ve been reading a lot of stuff about how early can you really test for an accurate reading. And a lot of it was saying a weekish after fertile window and others were saying just wait till your missed period cause you’ll get a better reading. Reason I’m asking is cause I have another week till my period but I’m also a smoker. And I 100% want to know so I can quit right away. I know I should quit now but as sad as it sounds I feel like if I’m pregnant it will give me the push I need. Also I want my baby healthy if I am... what do you guys think!?