I'd like to ask you to share your calendar's with the organization so it's easier for people to plan meetings (i.e. if you planned a dentist appointment everybody can see where you are, or if you're full all day they might want to check if you're 100% full or just blocked the whole day for an important deadline, but they could probably request a short sit down with you). For really private stuff you can check "private" and then nobody can see your item.
This is how you do it:
Set your Working Hours
Set your working hours using the google calendar setting below (tab: General)
ANDif you work part time or odd hours (i.e. 7 hours on some days) block these non working times in your calendar with a recurring meeting (time set as busy, not free).