According to a post on Reddit, some U.S. consumers are already receiving their replacement Samsung Galaxy Note 7 devices, as multiple consumers commenting in the thread state that replacement units have showed up at Best Buy and that they had received emails of the replacements being available. While this only seems to be limited to Best Buy stores so far, replacements devices were likely expected closer to the September 21st date that has been mentioned. Having said that, Samsung did state officially that September 21st would be the latest that safe replacement Galaxy Note 7 units would be available. Sprint later confirmed that they would have replacement units available no later than September 21st as well, which opens up the possibility that they could become available before that date.
For consumers who have purchased their devices through Best Buy, there are notable details that could determine when you get your replacement, being that Best Buy is informing customers that replacements are first come first serve, meaning that you'll want to go in as soon as possible to receive a new, and safe unit. The same goes for any customer who has pre-ordered a new Galaxy Note 7 as per the exchange and replacement program that Samsung issued after the recall, placing more urgency on getting to a local Best Buy store if consumers want their replacement devices at the absolute earliest time possible.
Not all local Best Buy store are guaranteed to have replacements in at this time, so those who are having to go through Best Buy for their replacement will want to check with their local retailers first to see if any of the safe Galaxy Note 7 units have come in. The initial Reddit post states that they received their two replacement Galaxy Note 7 units in a Michigan store location, while another poster on the thread states that they are receiving their units from a local Best Buy in Florida, so it's quite likely that other store locations around the U.S. will be getting these in over the next couple of days if they haven't already. Since the units are first come first serve, those who may have placed a pre-order for a new Samsung Galaxy Note 7 as part of this recall could end up with a different color of the device than what was placed in the order, depending on if there is any stock available.