Breast pumping questions

I feel stupid asking these but would feel even more stupid asking a lactation consultant.

When I write the times of my pumping on the bags do I write what time I started or what time I finished?

Also, when power pumping I do the hour like it says(pump 20, rest 10, pump 10, rest 10, pump 10)but I pump every 2 hours. So if I start at 4 and get done at 5, do I pump again at 6 or 7?

I just want to make sure I'm not over doing it and I definitely want to make sure I don't give my baby bad milk by writing the wrong time!