The current date and time. One timestamp is the old time_t, the other is the newer 64-bit timestamp that counts milliseconds. It won't overflow for a few million years.
A milestone en route to the overflow: the timestamp in base-10 hits 2,000,000,000 in 2033.
And finally, the last second before the overflow and the overflow itself.
Pre-Year 2038 (32-bit)
Year 2038 (32-bit)