PeeOnAStick.com tells me that a home pregnancy test (hpt) can read positive as early as, oh, heck I don't know, whatever, but it's really low threshold levels for the brand I buy. I buy Dollar Store brand (or maybe it's Family Dollar) which is distributed by Inverness. The official rated sensitivity is 50 (which is micrograms of hCG per deciliter, I think).
Anecdotally, you can get a + test at 10 dpo or <10 mcg/dL on that brand despite whatever the official sensitivity is. With Chuck, at 12 days after trigger, which is probably 10 dpo, I was at 34 mcg/dL (which is really low for a successful pregnancy...which he is, as he pees on the potty and occassionally sleeps through the night). I am 7 or 8 dpo right now. hCG doubles every two days, so let's work backward on Chuck's numbers.
10 dpo 34
8 dpo 17
6 dpo 8.5
Right now, I am about 6 or 7 dpo, so I would be between 8 and 17, which officially would not show positive. So, do I waste the buck in the am? Yes, I will. I had a routine exam last Monday (which apparently in the throes of ovulation) and was given strict instructions that with my history of luteal phase insufficiency (low progesterone unable to sustain a pregnancy) I need to know ASAP so a progesterone number can be run and supplementation offered, if needed. I guess then I will test every two days after that until I get my period or I get that mystical second line. Which if we're being honest here, I do not expect, but I hope (or I don't hope, whatever....I'm not getting my hopes up).