How long does it take for the temporal lobe to convert short-term memories into long-term memories? GRACIAS!
A good night's sleep is known to improve recall the next day, so it appears likely that some process of memory consolidation is operating several hours after exposure to the items being committed to long term memory.
I'm sure it varies from person to person and isn't completely well-understood. If you see something truly moving or terrifying, you're likely to remember it vividly.