Every other article and professional I've spoken with has said 7-12 days. Regardless it is always an estimation and the GREAT news is that your levels are rising strongly!!! Praying for a sticky little bean!
O WELL THE DR SAID ONCE THE EGG IS FERTALIZED IT ONLY TAKES 3 DAY TO IMPLANT
Most likely baby IMPLANTED on the Wednesday before your blood test. There's no way you could've conceived and gotten a positive in 5 days, even with a blood test. Implantation occurs 7-12 days post ovulation.
Anyway, CONGRATS!!!