Can i do army rotc for my first two years of college, then my last two years do afrotc or nrotc?

It would be tough if not impossible. If there's a nearby school (within an hour's drive or so) that has an AFROTC program, there's a good chance they'll accept you as a "cross-town" cadet. So, you'd be able to go to your two-year college, commute to the university where AFROTC is located and participate in it there, then (if you get selected for field training), continue the program upon transferring to the school after you're done with your two community college years. If you have a nearby AFROTC university, contact their staff. They'd be happy to talk to you.

NROTC expects you to be in college for four years. If you roll in with two years left, NROTC won't even take you (especially the Marines). You might be able to do PLC, however...

You can switch after two years, but there's no particular reason to do so. You can hold off on ROTC until you do your last 2 years and contract with NROTC then. There's no need nor particular advantage in starting off with Army ROTC for 2 years.

You can, but don't expect a scholarship. Yes people switch, but if you switch, you lose the scholarship you had and possibly may not get one from the new program. Prior to your junior year in college, you are not obligated and can quit at any time (which is what you would be doing with the first program). Also, just because a college does not have an ROTC Program, it does not mean that AFROTC or NROTC is not available. My university had students cross enrolled in the ROTC program from 6 other colleges because they did not have ROTC programs at the college itself. So they took all their classes at the main school, and traveled once or twice a week to the university for just ROTC.

It is currently extremely competitive to gain an Nrotc Scholarship in the College Program or Advanced Standing without a scholarship and likewise with Afrotc, in so far as attaining a Field Training slot and an Enrollment Allocation for the POC(Professional Officer's Course) With Afrotc, even Scholarship Cadets compete for an Enrollment Allocation. Nrotc Scholarship Mids do not compete for Advanced Standing. In 2011, 45% of Afrotc Cadets earned a Field Training slot. Nrotc College Program Mids compete for Advanced Standing and Afrotc Cadets compete for an Enrollment Allocation during the Winter of Sophomore year and at the time, you would be an RotcCadet. College students can apply for 4 year Nrotc high school scholarships as long as the student has 30 semester units or less at the time of submitting the Nrotc Scholarship application and is not already in the Nrotc College Program. You could apply for the Nrotc high school scholarship for Fall of 2013 now and then if not awarded, apply again in the spring of 2013 for the Fall of 2014, all the while participating in Rotc as a non contracted Cadet or just simply taking the Rotc classes. After one semester of college, could also see a Marine OSO(Officer Selection Officer) and apply for selection as a Plc Officer Candidate. Good understanding of Nrotc by reading the Faq on the website of the nation's original Nrotc Battalion founded by Fleet Admiral Chester W Nimitz: http://navyrotc.berkeley.edu/faq.shtml More helpful Faq, scroll down: http://www.colorado.edu/NROTC/faq.html Nrotc College Program v Scholarship Program: http://nrotc.missouri.edu/programs.php Plc: http://officer.marines.com/marine/making_marine_officers/commissioning_programs/platoon_leaders_class http://officer.marines.com/marine/making_marine_officers/commissioning_programs Oso: http://openbah.com/marine-ocs-articles/marine-oso-city-list Good understanding of Afrotc; http://airforcerotc.berkeley.edu/_afrotc-program.htm Helpful to read all Faq under each tab, Scholarships, College Life etc; http://afrotc.com/help-center/faqs/ Good Luck!