i would wait untill 2 weeks after your period is due, just to be safe, and try not to think about it, else your period could take longer to come....strange, i know, but true.
if your cycle is regular, most over-the-counter tests will give a reliable result on the day your period is due. There are some that will give a result up to 3 days before your period is due, but as pregnancy hormones may be still be very low, there is an increased risk of a false negative result.
The best method of pregnancy prediction is the word NO, or contraception used by either party. There is no excuse in this age for unwanted children and the risk of STD,s
After ovulation it takes at least 10 days for implantation to take place, which is only really useful if you know when you ovulated. You could try one a few days after you are due your period as the hormone will be get stronger by the day by then. There are lots of forums around to get advice, try www.ovusoft.com, they have some great message boards. Good luck, hope you get the result you want. :o)