Starting to bbt

Hi guys I started to bbt, I got a peak on the 8th I've done 2 temps, did they have to be done at the exact same time or does itatter by a couple of mins, my temp has gone up slightly. But I'm guessing can't really tell much because I hadn't done it sooner, due to my thermometer breaking. Had to get another. Do you guys have charts that show the difference in ovulation,pregnancy and period.