There is no regulation that says you have to do it, but there is also no regulation preventing a CoC from ordering you to do it. Your best bet is to talk to your CoC and ask if they need exact dates, or if they need rough dates. Also, ask if there will be flexibility based on staffing needs, if they want exact dates.
I personally find the idea of planning dates for my leave a year in advance ridiculous, but there are people who want their year planned out in detail. Could just be that the boss is a detailed planner, and doesn't understand that not everybody else works that way in their personal life.