When is it too late to quit smoking cold turkey while pregnant?

I just found out I’m pregnant, yay! I havent gone to the doctors yet but I estimate that I’m anywhere from like 3-6 weeks pregnant. I smoked around a pack a day before I was pregnant and I dont want to quit cold turkey if there is a chance that it would do more harm than to just keep smoking. So slowing stop smoking or is it perfect timing to just QUIT? Legit answers please. Thanks!