I got a + HPT when I was pregnant with Brock at 12DPO - a nice strong one.
I got a + HPT with the previous short lived pregnancy at 13DPO - a very faint one.

Try to leave it til you are overdue for AF though. I only tested so early as I was pretty sure I was pregnant as I was temping and had implantation dips. I felt exactly like I was going to get AF. I had no traditional early pregnancy signs apart from tiredness as it was too early for them to have set in. I always found the months that I "felt pregnant" I never was.

One way of avoiding testing now would be to purchase HPT's over the internet. They will take a few days to get to you and that would stop you testing (if you can keep out of that particular aisle in the shops). Lullaby conception tests are cheap and very accurate. Trust me, testing early can end up working out to be a very expensive hobby.