BBT questions for any one that can help.

Does it matter what kind of thermometer you use? When is the best time to start taking your bbt? I know you take in first thing in the morning before you move around or even get out of bed. I meant like what time during the month. I would like to start keeping track of my bbt and CM so I'll know when I ovulate. My DF and I have decided to wait until, at the earliest June of 2015 to TTC. I decided that it's never to early to start getting to know your body better than you already do and I'd like to do this to make sure everything is around the same time. So any advice and answer to my question are greatly appreciated. Thank you.