QUEST FOR REWARDS From Caesars Total-Rewards Members Between January 1 And March 31, 2018.

Another way to build your Tier Credits for 2018.
More information.
Looks like in that period of 3 months you can earn up to 1,800 Tier Credits per day in Las Vegas, only 9 days to get Diamond status or 14 days to get free access to Diamond Lounge.
Or 84 days, basically stay there all 3 months, to get 7-Star status.