A calculation I did some time ago:

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 blocks before first block halving

Current block: ~129405

133.333-129405=3928 blocks to go

3219*1 min = 3928 min = 65.5 hours = 2.7 days to go