Hey Jessy, I would suggest buying cheapie OPKs either on earlypregnancytests.com or on
ebay
They are a ton cheaper, but not as clear as the more pricy ones (Answer, First Response, etc). What I do is start using the cheapies around cd 11, and when they start to get darker, then I use the more expensive ones to confirm a + result. On the cheapies it can be harder to tell a + vs a - !