A date is really just a number attached to an event, which means Days 8-10’s number-word dictionary applies directly. The move: pick a picture for the event itself (or a keyword sound-alike for a name), then convert the year to its picture-words using your phonetic dictionary, and fuse the two into one image.
For a year like 1969, you’d typically only need to encode the last two digits within a known century, 69, since the century itself is usually obvious from context. Convert 69 to its picture-word, then fuse it directly onto your image for the event so the two surface together.
For a timeline of several events, chain the fused images in chronological order, exactly like Day 3, so walking the chain also walks you through history in sequence.