♥When a woman starts her period, is that the first day of her cycle?
Yes, usually you start counting on the first day of red blood. This is cycle day 1
♥If a woman has an average cycle (28 days), when is the earliest possible she could ovulate?
It really depends. The time between when you ovulate and when you start your period is called your luteal phase. These *usually* range in time from 10-14 days. So, for example, if you ovulate on cycle day 14 and you start your period on cycle day 28, you have a 14 day luteal phase (aka LP). You really need to know your LP before you can decide the earliest that you would ovulate on a normal, 28 day cycle, and to know your LP, you need to know when you ovulate
However, I would estimate cycle day 14, which would give you a 14 day LP, which is at the more lengthy end of the "norm"
♥If a woman has an average cycle (28 days), when is the latest possible she could ovulate?
See answer above. If you had a short LP, you could ovulate as early as cycle day 18-20. Again, it really depends! A LP of 10 days or less is a bit of a cause for concern, so if you notice that your LP is 10 days or less, you might want to consider using progesterone cream, and of course, talk to your dr. first.
♥If you ovulate early or late in your cycle, does that mean your whole cycle will be less days than it would be if you ovulated on time? For example, if a woman normally has a 28 day cycle and ovulated on day 12 instead of day 14 like usual, would she get her period exactly two weeks after ovulation? Or would she still get her period on the 28th day like normal?
Okay, using your example, if a woman who normally has a 28 day cyle and usually ovulates on cycle day 14 ovulated 2 days early on cycle day 12, this would *usually* mean that her period would come 2 days sooner. So, a 26 day cycle instead of a 28 day cycle. Your ovulation date can vary, but your LP is usually the same. So, if your LP is say, 13 days, you can predict that your period will start 13 days after you ovulate.