When do I take my clomid??

Hey there ! So AF came today and I was so so disappointed , just like I have been the last 2 years... But now it's time to take my first dose of clomid and I was wondering when is the best time to start my 1st dose... All this research online is confusing me and I really don't think my doctor gave me a good answer on when to start taking it... Please help :))!!!!