With my first pregnancy I tested before AF when I was going off the pill, it took three cycles being off the pill (but the first two I think were the hormones leaving my body because I felt pregnant the entire time!) So I had two negative's (which were true), then with the third cycle I was SO tired and couldn't eat much with out throwing up, so I tested the day AF was due.
The second and third (current) pregnancies I waited for AF to be due to test and got positive!
I like the clear blue digital ones, and there not cheap, so I didn't like to test TOO early. Also, the second and third times we got prego right away!
Good luck!
I tested a day after my AF was due and got a "pregnant" on the digital. I've heard of some women being negative for awhile before getting a positive and even heard of some being negative on HPT's and got a positive blood test at the doctors.