The reason you should only temp in the morning before you get out of bed or do anything,is because your temp varies through out the day your whole cycle.
I wanted to try out my thermometer to see if it was working properly so for the past few days Iv been temping at 7am (which is the temp I add to my chart),then again in the afternoon and again at night just to see if it varies,and my temp is always higher at night than it is in the morning and in the afternoon its sometimes low,depending on the day..but those temps dont count.You should only take into consideration your temp in the morning after a good nights sleep which is when your bodys temp is normal and your body is relaxed
Also,before you can make anything out of your temps,you have to be charting for a little while.A while ago I took my temp 2 days running (silly me! lol) and I asked what they meant,and I was told that when you have nothing (no pattern) to compare them to,they dont meant anything kwim?