A constant themes in personal financial management is to "pay yourself first". You should put money into savings and investments before you create your spending budget. It creates good habits that help you in the long run.
Time is money so I think you should pay yourself first in time. Because you own your calendar, pay yourself in time first. Block off your calendar for what you need to get your most important things done, then let others take your time as appropriate. This ensures that you are using your time in a way that benefits you.
How does this look? I do this is a few different ways.
Blocking off key time. For example, I try to block off my Friday afternoons for weekly reviews and do this consistently. I set these up as recurring meetings that mark my time as busy. Obviously I can adjust it in extreme situations, but I make sure it is there.
I block off time early in the morning. Most calendaring systems have a feature that enables you to indicate when your workday starts and stops. I set mine so that it starts at 8 am (any time before that will be busy), even though I may start at 7 or 6 am some days. This enables me to have mornings to get things done and prepare.
Block off time for "deep thinking" (H/T to Cal Newport). This is blocked time to do some focused work. I don't put this on my calendar every week, but pick times when it will be used (right before a presentation to finalize and practice, when I need to do strategic thinking).
This is choosing how to use your time to get the important things done. Anything else is letting other people use your time for what they think is important.