Clarification, and or Communication is key. Make sure you know who's responsible for setting up your venue. This information will have been forwarded to you, the planner and or the day of coordinator.
Usually it is the responsibility of the venue to have your area ready for vendors to come into the premises to give you the look that you were contracted. Venue's normally give each event 2-3 hrs for setup, up to 4 hrs for event, and 1-2 hours for clean up.
If venue is not responsible for set up, this should be clarified upon signing of contract; and information should be relayed to all vendors so that appropriate time can be allocated for such a task.
If venue is not ready and prepared for vendors to come in and setup their decor, food etc.. it will delay the event by 1-2 hours depending on what's needed for vendors to proceed.
Delays can incur additional time and charges if a vendor has to come in and set up a space that is not prepared to receive them. Vendors can also choose to charge; and or not to proceed or may determine what is most important to client if (vendor) has the task of setting up an area to proceed with the event of the day. When making such decisions, vendor may and can omit certain items that were to be there for the event and can decide to not refund monies paid for items that were there on premises; due to time constraints.
Therefore Communication and Clarification is key when it comes to venue; ask questions and more questions, check and double check to make sure that there are no mistakes of responsibility when it comes to Venue Setup.
Last but not least; it is very important to know what the venue allows and disallows as far as the use of electricity, ceiling draping etc.. For instance If a venue does not what to allow use of additional electricity for lighting etc; then when your DJ or Decor Designer tries to utilize utilities that are not allowed; it makes for a difficult incident. Therefore items brought to premisies for use and are not allowed; vendor can not be held responsible and does not have to refund for items brought for use due to venue constraints. So check, check and double check what is allowed. Venues ususally tell you all that they allow or offer complimentary in your contract that would cover uplighting etc... Ask questions and more questions, check and double check before you pay for a service that is not allowed.