I need to measure the conductivity of tobacco leaves as they are undergoing PCD at timepoints of 6, 12, 18 and 24hrs.

The problem that I have is if I sample the leaves at 6hrs (for example) I then have to incubate them for at least 2hrs before measuring. If I do this then will the measurement that I take be of 6hrs or 8hrs (time including incubation)?

Most papers that I read are studying it at 1-3 days and so 2hrs doesn't make a difference whereas at shorter timepoints, the 2hrs could make a big difference.

I just want to know if I should sample at 6hrs or 4hrs to take the incubation time into account.