There is a variety of literature that outlines how this works but I figure it is worth looking at it from a school administrator lens.
For tasks that are important and urgent, those need to be done now. For example, if a fight breaks out, you need to deal with that fairly quickly to ensure the safety for all. Similarly, if a student is in crisis, stop what you are doing and help them through it! Fortunately though, very few things in education are emergencies. Early in my career I felt like everything fell into this category. With more experience I have found that many of the things I thought had to be done immediately, often don’t.
For things that are important but not urgent, you have some time on those. They could run the gamut of preparing for an important parent meeting, reviewing a student’s educational programming or even something as simple as making an agenda for the upcoming staff meeting. These you can make some decisions about to do later and plan a time to address these issues. Because they are important they will probably move into the important and urgent quadrant anyhow. Ideally, you want to make sure you have had time to come up with a plan so you are ready for it. This helps you to make a much better decision when the time comes.
When things that are not important but urgent, delegate. The urgency requires a response but probably does not require your personal response. Running a food drive for example is something that has a definite deadline, but does not require you personally to oversee. These are also great opportunities to build capacity in your staff, or your assistant principal if you are fortunate enough to have one, and show them that you trust them to oversee projects. The important thing here is that you do not try to jump back in and micromanage tasks. Doing this defeats the purpose of you delegating it in the first place, as well as erodes trust since you are demonstrating that you did not think they could do it without you.
In the final quadrant, tasks that are not important and not urgent, don’t do those at all. Toss them in the garbage or delete them from your computer. Granted that these seem to be few and far between since everything feels urgent. Some of them may even be things that you would like to do but remember that unless you feel they are important, they will drain your time and resources. You may wonder about personal projects (like writing a blog!) since they may not be seen as important or urgent. However, generally these sorts of projects have some sort of significance to you since you are chosing to take them on, in which case they gain importance through your interests. Granted they still often take a backseat to important and urgent, but, these are the exception to cutting them out of your day.
This all seems easy when laid out in this way and is much more difficult in the moment to analyze each task in that way. The good (and bad) news is that these tasks keep coming up again and again so you keep getting opportunities to make changes to how to deal with these things.
One thing that you will have to decide for yourself though is what you feel is urgent and what you feel is important. For example, I make time in my day to try and sit with staff at lunch. It could be argued that this should be in the delete block, but I feel that it is an important time to connect with staff, find out how they are doing, and learn about them as people rather than just staff. Connection and relationships are hugely important to me so they tend to move higher on my matrix.
There are lots of ways for administrators to allocate their limited time, this is just a suggestion that I find helps me. It doesn’t mean I always get it right, but it does mean I get a few less of them wrong.