I'm in the UK. 28 days of paid vacation time is the legal minimum (22 vacation days, plus 6 bank holidays). I get quite a lot more. Some places around the world have higher legal minimums. People in Brazil all get at least 30 days.
Maybe I'm unusual but I rarely have any plans further than a couple of months ahead. Whether I'll be going on any long trips in the next 12 months isn't something I have any idea about yet. It depends on loads of factors (money, weather, work, whether I can pick up a bargain, etc.)
A month or two in advance is just fine, most people can do as much. They do know how many days of vacation they get though, and it's unlikely to change, so any plan you have you keep.