How long after implantation can I test with First Response?

First Response Early Result tests are known for their high sensitivity and claim to detect hCG up to 6 days before your missed period. Since implantation happens between 6 and 12 days after ovulation, you can potentially test with a First Response kit as early as a day or two after implantation, but results will be more reliable as you get closer to your missed period. Waiting just forty-eight hours longer allows your hCG hormone levels to double, giving you a much bolder and more confident positive result that removes any doubt.