Out of the office
Time off is about the time you need, not about a quota.
When in doubt: 2–4 weeks is a good bandwidth.
We stick to the commonly used national holidays. That said, we are a small team, and there are times where work will need to be done 24/7, regardless of holidays. Remember, flexibility goes both ways.
Agree on your time off with the team.
Put your time off on your own and the team calendars.
If you're sick, that sucks, go/stay at home.
Let your team know that your are sick and when you expect to feel better.
Update everyone on how you are feeling if it takes longer then expected. Stay home until you are better.
Most importantly, don't feel guilty for being sick.