If the temperature is in the 70's its usually safe to walk across the deck with clean shoes after about 2 hours.  We don't recommend scheduling any dance parties for at least a day or two.  If the wood is in the full sun, that will help the stain dry a little quicker.  When the wood is in the shade, or the temperature is cooler, it can take longer for the stain to dry.
To replace deck furniture before the wood is completely dry, you can use shoe coverings.  These slip on covers will prevent you from tracking dirt into the finish.
Older wood that absorbs a lot more oil can also take longer to dry.