Let's try a calculation (please correct me if I am wrong):

From OP:
USDE max supply: 1.6 Billion (1,600,000,000)
Block halving: block halving every 1/3rd of the coin's total supply
Time per block: 1 min

There are on average 4000 coins in 1 block:
1.6 billion / 4000 = 400.000 blocks

400.000/3 = 133.333 coins first block halving

Current block: ~61850

133.333-61850=71483 blocks to go

71483*1 min = 71483 min = 1192 hours = 50 days