Shipping and installation
As soon as the FAT is signed off, the supplier will start packing the system (hopefully after a full backup has been performed!) ready to be shipped to the site.
The time required to package the system, ship it, and install it on site could run into weeks, and this needs to be carefully managed so it is not on the project critical path.
I always use this time to fix FAT issues on a parallel system to save time, and I fully recommend this if at all possible.
If the OTS is shipped to a different country, then this process could be longer, and getting through customs should be considered in the time allowed for shipping and installation.
The OTS location should be discussed and finalized well before shipping starts. A room should be readied to receive the OTS with a full power supply, Uninterrupted Power Supply (UPS) (if required), enough power points, access to large equipment (large cabinets, for example), and large enough lifting equipment if required...