Progesterone is a hormone released by the corpus luteum in the ovary. It plays important roles in the menstrual cycle and in maintaining the early stages of pregnancy. It may also be involved in the growth of certain cancers.
I've been following various people's posts about the GRE for 10 months now. Some people don't study at all for the GRE, some study for a weekend, the average is about 2 to 3 months, and some study for a year or more.
Answer: For fall admissions, you should plan on taking the GRE in October of your senior year. If you miss October, December might also work, although some schools may not get the scores in time. (It can take as much as six weeks for the scores to become available.) Many application deadlines are early to mid January. However, a few are mid December. For spring admissions, contact the particular graduate school.