Most times FedEx does deliver your packages on the expected delivery date.
However there have been times where a package was delivered to me by FedEx a day before the expected delivery date.
Also sometimes delays can happen such as severe weather that may cause a day or two delay in the delivery date of your FedEx package but it's rare that it happens.
Most times you will get your package from FedEx on the expected delivery date.
Some packages require a signature for the FedEx package and some packages will just be left at your door.
If you're gone and the FedEx package requires a signature then the FedEx driver will leave a door tag where you can sign the door tag for your signature and they will release the package.