Sometimes it works out fine to wait to the last minute to inquire about renting your storage unit but there are advantages to allowing time to do research. The sooner you start looking the more potential options you will have. Some storage facilities do not allow you to reserve space without renting the unit first while other locations may hold a unit for a short period of time. If you are flexible in when you need your space you can visit or call more places and see what the differences are between them. This allows you to determine for yourself how important those issues are. Visiting a facility first, and checking out sizes, will help you better assess what space is needed. Do you want a little elbow room to move around in so that you can sort through things or do you want to rent the smallest space possible, packing stuff as high as you can reach.
The security offered can vary widely. Some places have each individual unit alarmed. Others may offer camera surveillance. Some facilities have gates and fences that restrict access. There are single level storage facilities that you just pull right up to your storage units’ door while other places may require you to use an elevator. If you pick a location that has a loading dock, the dock may have been originally designed for commercial vehicles and will therefore not line up with the backend of your rented truck. Instead it may be a couple feet higher.