dantet21: You were concerned about your PFT - especially pull ups. I assume you have googled and found the Marine PFT test description and scoring tables. A 300 (max score) on the physical fitness test is impressive but is only one part of the criteria considered when choosing scholarship recipients. I don't feel that scoring a 300 is essential or "makes it easier". Every year there are candidates with a 300 who don't get the scholarship and those with lower scores that do. While the Marines stress physical fitness, they are looking for so much more. My recommendation is to get working on this and shoot for a 1st class score - the higher the better. Work out hard and often.
Regarding timing on your application - My advice is that the best prepared application is better than the earliest submitted application.
If memory serves me, the first Marine board is typically in late October or November. But do not take that as fact: the timing and dates are always confidential and the best way we have of pinning it down is when people start writing posts about their selection for scholarship and then we can "backdate" the time frame a little. I would recommend that you plan to have the application completed in early September of your Senior year. This would involve getting the on-line application, references, interview and PFT all done.
The application includes two essays. I would spend some time formulating your answer and then write the very best essay you can. Work hard on these application essays. Have others read them. Speak to active duty military members, veterans, and read books about being a military leader. In my opinion, these essays need to convey the essence of why you want to be a Marine, why you will be a good leader, what you have to offer the USMC. This is where you can stress your understanding of leadership and you experiences as a leader. Write, rewrite and then rewrite again - making your essays better and better. Make sure your English teacher and others proofread them for you.
ckwitzel makes a good point about references. Choose wisely. With the school year winding down, suggest you speak to them live and ask them for the reference. Stress the importance, what you what highlighted etc. If they don't have time you may have to wait until School starts again. Some people might appreciate the heads up and use the summer to work up their response. I would hit the guidance office right away when school starts next fall to get your transcript out.
The 5-school strategy is a tough one. There are lots of comments about this subject in this forum. You need a balance of schools you are fairly certain you can get in which have NROTC and your intended major, stretch schools, distance, family budget, etc. In-state vs out of state vs private is a tough one to predict as is your own personal ranking. Suggest you give this a lot of thought, consult the guidance provided here and then select them in the order that makes sense for you.
Worldtraveler: The "Application Information Checklist" states: "We highly suggest you contact your coordinator/recruiter to have them review your application before you make the final submission. Once you click on the final submit button, you will not be able to access it or make changes." My DS worked with the local recruiter who called on his high school. This is not this Marine's primary responsibility BUT apparently in our area, the OSO (Officer Selection Officer) must have a great working relationship with the local recruiters. The local recruiter checked over my son's application before submitting, answered questions and was a real asset. If this avenue doesn't work for you, I am sure you can find the local recruiting district for your area and obtain the name of an appropriate point of contact for this process.
Once the application is reviewed, completed and submitted on line, you will then be contacted to schedule an interview with a Marine Officer and take a Physical Fitness Test. An official photo will also be taken. Most often these are all done on the same visit. Prepare for your interview. Make it a good one. Make a good first impression. Answer questions with honesty and sincerity. Look to this forum for suggestions on what to expect. Have some questions prepared for the interviewer.
Final point, you will read of people with "better" records who didn't get a scholarship and others with "weaker" records that do. The board's decision is based on your application, your grades, your test scores, academics, demonstrated leadership, essays, interviews, physical fitness test and the needs of the Marine Corps. That last category (needs of the USMC) is the one that can really swing things from year to year.