The two treasures come usually on a monthly basis. From what I've seen, it alternates between Jin 1 and Jin 2.

This time is Jin 1, but when it's gone, the next time a Time Limited Treasure, or TLT, pops up, it'll be Jin 2. Jin 1's Yagura+Fu, Jin 2's Han+Roshi. I'm simply using this due to not wanting to correct the earlier messages and realizing that I already said Jin 1 and 2. It's not to be confused with the actual non TLT Jin 1+2.

They usually come out on a monthly basis, usually near the middle of the month. So about two or so weeks in between each one's appearance. Jin 2 will likely appear next on either the 12th or 19th of September, and after this week's events, Jin 1 will likely re-appear on the 10th or 17th of October. I'd be willing to bet they'd be the earlier dates.