O is 24-48 hrs after a +opk, but if you get several +opks in a row ( see my chart in my siggy) then it can be after the first or 2nd opk
Even if you get a + opk, you may not O. Your body can rev up but not actually release an egg ( annoying trust me I know) This is why most of us chart temps it's the only way to verify the egg release as temp rises and stays up.
You can ramp up but not O, then O later in cycle. Only way to know is to chart tho sorry- for ex if you get a +opk but temp doesn't go up after cpl days then O prob didnt happen. In this case, we would keep using opks to watch for a 2nd surge and hope that time you O.