Yes, but you will be at a disadvantage. When I was in ROTC, Guys who joined the program on a 4-year degree but joined a year late were told that since they had less ¨face time¨ with the cadre, they would have some catching up to do to improve their cadet ranking and improving their chances of a pilot slot.

THings may have changed since I commissioned in 2006, but we were required two PT (physical training) sessions per week, leadership lab which lasted 3hrs per week, additional activities such as attending dining-in and dining-out (some were required as part of learning objectives), and then there was class. Each year is divided into its own category.
AS100= freshman, 1 hr per week, for a grade
AS200= sophomore, 1 hr per week, for a grade
during the summer, you have to attend Field Training, lasts approximately 4 weeks and you get yelled at a lot and march and stand at attention etc, kinda like basic training but i think the move has been to make it similar to OTS
AS300= Junior, 3 hrs per week, for a grade
AS400= senior, 3 hrs per week, for a grade

as a 2 year student, you will only take AS300 and AS400 classes, and your Field Training will be 6 weeks (i think, maybe 5 weeks), and the additional time will be ¨Academics¨ which covers the material from AS100 and AS200.

For students who take more than 4 years, their 5th year is usually called AS500 or AS700, something like that. they always change it, but back in the day they only required AS500s to attend 1 PT per semester and I think two leadlabs per semester, but by my AS500 year it was changed to attending all PT sessions and half of all lead labs. things may have changed.

keep in mind, these are the bare minimums. the guys who got pilot slots were usually going above and beyond. you will have opportunities to have leadership positions which involve being in charge of projects. For example, we had a protocol officer who was in charge of putting together the dining out, which is like a ball/prom (best way of putting it in civilian speak). it included booking a venue, food, DJ, guestspeakers, decorations, someone to sing the national anthem, color guard arrnagements etc... your performance in these projects directly affects your cadet ranking, thus affecting your chances of getting a pilot slot, and totallying bombing it will hurt you. there were lots of jobs, including training younger cadets, cadet wing commander, vice commander, DO, morale officer, safety officer, CAP officer... each ROTC unit may be different, I can only speak for mine. there are also opportunities to do things not required, but improve your standing, such as color guard, volunteering for fundraising events (which at my ROTC detachment included cleaning the football stadium after games), and your attendance to nonmandatory events will be noted (for the positive or negative, depending on how well you present military decorum). basically, if you want to stand out, the bare minimum won´t cut it. same goes for being on active duty (XO duty and putting together a holiday party for example will get you a nice stratification :P)

from what i remember... scholarship cadets were committed after 1 year. non scholarship cadets were committed after completing field training.
AFOQT was done first year. TBAS (BAT at the time) was completed in the summer approximately 2 years before commissioning, all your info for competing for a slot went in the fall approximately 1 year and 7 months before commissioning, pilot slots were handed out in the spring about one year and 3 months before commissioning. medical flight screening was conducted in the summer one year before commissioning. add 7 months to any figures for fall graduates. for those of us who were 4 and 5 year cadets, by the time we were applying for a pilot slot, we were already locked-in to a 4 year committment. if you never get selected for a pilot slot, most guys still got selected for navigator or air battle manager. guys who got medically disqualified from any flying usually went on to be intel (this was my case) or acquisitions (my friend´s case) or communications or whatever they had on their dream sheet not requiring a flying class medical. sucks but true, as a cadet you´re there to train to be an officer first, not a pilot candidate.

guys who didnt get a flying slot out of ROTC could apply on active duty as long as they didnt exceed 5 years as an officer and could meet the age limit, but most guys i knew who applied from within active duty didnt get into UPT until their second or third application.

hope I could help.