Most dorm shopping lists are organized by category — bedding, storage, tech — which is useful for browsing but not for actually deciding what to buy when. This one's organized by timing instead, because a few of these decisions genuinely shouldn't be made before move-in, and a few can't wait until after.
Buy Before Move-In
These need to exist before you arrive, because you'll need them the first night. Twin XL sheets sized correctly the first time, not something you'll discover doesn't fit once you're already unpacking.
A shower caddy, ready to go for the first trip down the hall.
Set Up on Move-In Day, Before Unpacking Everything Else
A surge protector, positioned and plugged in before the room fills up with boxes.
A first aid kit, unpacked and accessible rather than buried — move-in day involves enough lifting and assembly that this is worth having out from hour one.
Buy After You've Seen the Room
Storage solutions sized to the actual closet and under-bed clearance, not guessed from a floor plan. A rug, if there's floor space left once the furniture's arranged — this is one of the most common "bought too early" items, since dorm rooms rarely lay out the way you picture from a photo. Wall decor and styling — get the functional setup right first; decorating a room that doesn't work yet means redoing it later anyway.
Decide With Your Roommate First
A mini fridge (usually one per room, not two). A trash can, if you're planning to share one. Curtains or any shared window treatment. A quick message before move-in avoids buying two of something a room only needs one of, and avoids the awkward first-day conversation about whose fridge is staying.
Skip Entirely
A standard (non-XL) sheet set, a full-size extra bookshelf your dorm probably doesn't have room for, and a printer most campuses already provide access to. See the full breakdown in things you don't need for college if you want the longer version of this list.
The general rule underneath all of this: anything that touches sizing (bedding, furniture, storage) is safer to buy early with real measurements in hand. Anything that touches styling or shared decisions is safer to wait on until you've actually seen the room and talked to whoever you're sharing it with.