literally, in the bladder.

I usually drink a ton of water/tea during the day and this whole, waiting 3-4 hours to use the bathroom before the OPK is causing me grief. I know in the big scheme of things, no big deal, but my body isn't buying that right now. Heh.
Re: Timing OPK use is a pain
I also drink a lot of water, as you should approaching ovulation (keep CM thin).
Here is what I do: I pee into my pee cup. If my urine looks pale/clear, then I discard it. If it looks concentrated, I use it. Sometimes that is 3-4 hours, sometimes not. You don't have to adhere hard and fast to that rule.
good luck!
DS born via unplanned C-section at 40w6d
Yup, I've done that too at times (mostly when I'm home b/c I have an endless supply of pee cups at home - if I'm out and peeing in a cup, I test whatever shows up in it).
My BFP Chart
Becoming a better role model for my daughter, one day at a time