If you choose to play by March 31, 2015, you can reach Diamond for even less action. During that time you get a special 50% tier bonus above and beyond all other matching and bonus tier offers (up to 25,000 bonus tiers). I think this was because CET wants to entice players nervous about the bankruptcy filing. So you only need to get to 10,000 tier credits by March 31, 2015.
So if on Day One you earn 2,500 tier credits, you get 5,000 bonus for a total of 7,500 tier credits.
Day Two earn 1500 tier credits, with associated 1,000 bonus for a total of 2.500 tier credits.
10,000 tier credits by March 31, 2015 has a extra 50% kicker added on April 15, 2015 which gets you to Diamond.
https://www.harrahsresortsoutherncalifornia.com/content/dam/total-rewards/PDF/total-rewards-PDF-5.pdf