Assuming all is equally important you first start by getting your station ready. By that I mean creating an area which will mentally keep you focused. Have your coffee, a good night's rest, and motivation. Then start calculating each tasks time frame. Which will take less or more time. People try to start on tasks that take a longer time to execute and blow off the ones that are faster to take care of. That is wrong. Finish the short tasks first to start checking off your list. The more checks their are, the more accomplished you will feel which will allow you to stay determined to continue. Now if a longterm task can be started such as setting a meeting for the future, then of course do that right away. In my line of work I will start a chicken stock right away since it takes 6 hours to simmer. Right after starting it, then I start prepping veggies and other small tasks. But my line of work doesn't always match what you are going through. Saving time is awesome. But thinking about time is what stresses people out. So don't rush. Keep at a steady pace and do the work. But don't feel like you are going to be late.