Do you mean how long before the seller hands it over to Fedex or UPS? If the order was booked today, personally I would expect it to go to the shipper tomorrow. As for shipping time....depends if you paid for overnight, 2nd day, ground...etc.
If you bought it from the Apple Store it should have shown on the main page if it is in stock or expected to be in stock in 3-5 days. If it showed in stock it should ship within 24 hours. Sometimes Apple will list items that they are still refurbishing in batches before they are done, list them as ships in 3-5 days, hence a short 'delay' in shipping when the item wasn't actually read to ship at the time of purchase anyway.
Ignore all of that if you didn't order it from Apple.