Some good reading!

Implantation

What is it?

After the egg has released it only has 12-24 hours to be fertilised.

Once fertilised in the fallopian tube the egg is sucked through the fallopian tube into the womb. It will arrive in the womb around 5 days after conception.

Once there the egg (also known as the 'blatocyst') begins the process of attaching itself to the endometrium by digging and burrowing into the lining and producing hcg.

How long does it take?

Just because the fertilised egg 'can' arrived in the womb at 5dpo it doesn't necessary mean it will immiediately start to implant, often the fertilised egg floats around for a while before decided to embed and dig itself in. It usually takes about a week on average for implantation to start but i can happen anywhere between 6dpo and 12dpo.

Implantation 'can' happen in as little as one day but can take up to 4 or 5 full days to complete and for the blatocyst to completely attach.

Over 80% of pregnancies implantation will occur between 8-10 dpo.

It can then take a further 2 to 4 days for your kidneys to process the hcg and secrete it into your urine so it can be picked up on a HPT.

If you experience implantation bleeding you should try and wait 2-4 days after it's stopped before you test (unsing a test at 25mUL or less) it is possible to still get a negative at this point, if you do, wait 48-72 hours and re-test (this is the time it takes for hcg to double)

Yeah but when can i test?

Detection of hCG depends on timing of implantation, so hCG can normally be detected in the blood between nine and 16 days after ovulation (HPT: 12-19 days after ovulation).

Okay so just say everything runs perfectly and the blatocyst arrives in your uterus at 5dpo and imlants in a day it is 'possible' to get a +hpt at around 8dpo.

However, on average it won't start to implant into the womb until 8dpo. Say once again you're lucky and it only takes a day to implant then you could on average get a bfp at 9po. Hence where many early test hpt's claim you can get a +hpt 6 days before your period.

Yet, bare in mind it may not occur until 12dpo and it 'may' take 4 full days to complete so that would take you up 15dpo. It 'can' then take up to four days for the hcg to be secreted into your urine so hello?! that's 18/19dpo already before you can get a +hpt. yes, this means implantation may not complete until AFTER your AF (Aunt Flo - menstruation/period) is due.

Infact, research found that 10% of pregnancies may not show up on a hpt on the first day of your missed period.