You need to contact an officer recruiter RIGHT NOW, because you have to be under 27 before the date of commission, from what I understand. OCS is about 3 months, and the application process will probably take AT LEAST 4 months for you to get a final select, probably more like 6 if not longer...so that's already 9 months right there. Keep in mind there is no obligation for applying, so the only thing you have to lose is the option (if you don't apply soon).
Since you've only got 11 months till you turn 27, you should really get the process moving ASAP. Maybe it is different for the marine corps, and if you are prior enlisted, you could get an age waiver. Make sure you read up on the physical standards, which can be found
here . Also, you should have a look at the anthro standards, which can be found around this site, just search for anthro or something.
Good luck!