Yes you are correct. Basically rate for swap is 1:4000 (NEW:OLD)
you should buy 0.3125 NEW ERC20 and transfer them to your wallet.
Then send all your OLD ERC20 to smart contract address for swap. 0x9AABC792478ca988c45d2C762c5e4265cb5bE39c
And wait when we will check it and send you 0.3125 NEW ERC20 more.
Totally you will have 0.625 NEW ERC20 after the swap.