Whenever you delete anything, it is immediately deleted from our storage. There is no “deleted” flag set or anything, where the actual file might linger around – it is erased.
However, you might notice delays like that due to the Content Delivery Network (CDN) we have on Snap.as. This makes photos load faster for viewers by copying them to servers around the world, to be closer to whoever is viewing them. But because of that, these servers also hold onto that content for longer, which may mean a little delay between deleting the content centrally (which happens immediately) and deleting it around the world.