Have you learned a lot about your anatomy and physiology while trying to conceive, or do you just wing it? I know that before I started trying to conceive I was sort of aware of when I ovulated, but I never gave it much thought. After trying to conceive I can tell you everything you want to know about cycles and pregnancy, and then some.
I know a ton more now that I have awesome apps like Pink Pad and Period Tracker. It takes all the guess work out for you. All you have to do is plug in when you start and stop and your symptoms. So easy!
Do they have options for basal body temperature, too, or just symptoms?
fertility friend is the app i use to track. :) i pay a decent amount of attention to my CM, but not enough to really track it with 100% accuracy. both times i've gotten pregnant it's happened in months where i've really been diligent about tracking my temperature. i totally believe that has helped expedite the process for us. we'll see how it goes as we get back into TTC mode this time...
The absolute earliest would probably be about 8 weeks postpartum. Your body isn't going to be able to prepare to ovulate until all of the pregnancy hormones clear your system. That takes, on average, 6 weeks. Then it usually takes another 2 weeks for actual ovulation.
When I was nursing my son, it took 8 months. My daughter, I got my period on her first birthday!