It's crazy that some employers expect their staff to plan their lives around their jobs to that extent. I have 12 days leave still to take between now and the end of January 2016 that I haven't booked in yet. I'll start to think about 2017 leave in about 14 months time!
Back on topic it's very difficult to make plans to Turkey of all places that far in advance. One Tunisia style event could change everything in terms of their tourism industry.