How to convince board to make a rental exception

I am a young 20-something who miraculously was able to purchase a condo in a high rise 6 months ago. It is truly my dream home, and I love everything about it - the unit, the people, the staff, and even the management company. I'm fully committed to and invested in the building and I intend to live there for many years.

However, I was just accepted to a year-long graduate program in another country, with a full scholarship. In order to take advantage of the opportunity, I'd need to rent my unit approximately 4 months before the 18-month waiting period required by the association has passed.

I'm planning on making an appeal to the board to see if they'd be willing to let me do so - with the full intention of moving back in as soon as the year is up.

Board members, if you were hearing a similar case, what would make you more willing to grant the exception? How early should I begin the process? Any insight would be greatly appreciated.