#1 - Updates!
Now is the time to run those updates that you have been ignoring on your laptop, phone, and tablet. If your laptop or tablet is owned and managed by your school, your IT staff may have already run updates for you. If so, take a look at what's new. If your IT staff hasn't run updates for you, now is the time to run them yourself.
Updates aren't limited to the operating system of your computer, tablet, and phone. Run the pending updates for your web browser and for your favorite apps. Sure, some features may change, and change is scary, but overall updates are good and necessary to keep your apps running as intended.
#2 - Dude! Where's my printer?
While you were away for the summer, your IT staff was hard at work updating lots of things to make life better for everyone who uses your school's network. You might find that old printers were removed and new ones were added. The morning of the first day of school is not the time to discover that you can't connect to a printer. Test print a page or two as soon as you can.
#3 - Can You See This? Can You Hear This?
Is there a new projector in your classroom? Give it a try as soon as you can. If it is projector that uses an HDMI connection, you might find that the HDMI is trying to carry the audio as well as the visual from your laptop. This could be fine if your projector has speakers and those speakers are loud enough for your whole class to hear. Otherwise, you'll need to figure out how to project your audio to a set of speakers. That process can be amazingly easy or maddeningly difficult depending upon your computer and projector combination.
Do you have an interactive whiteboard in your classroom? If so, make sure to run any pending updates to the software that it uses.
#4 - Freshly Filtered Websites
Your IT staff might have changed filtering services or settings over the summer. If that's the case, your favorite websites and web apps from last year might not be accessible in your classroom this fall. Make a list of the sites and apps that you previously used and are now filtered. Then calmly discuss the items on that list with the people who have the power to make changes to filtering.
#5 - Use the IT Department's Request System
You might think that "the squeaky wheel gets the grease" is the best way to get your tech problem fixed quickly. The reality is that your IT department is just as busy as you are and would prefer that you don't barge into their offices just as you don't want someone barging into your classroom in the middle of a lesson. If your IT department has a formal work request system, use it. If they don't have one, email them with your request.
By the way, many school IT departments take care of 3x-4x as many staff as their private-sector equivalents.