"The exact time will be announced 1 hour before launch with a countdown timer, and everything including final code, binaries, config files, nodes info, RPC, explorer, etc. will be made public when the time's up."
According to the @EthereumPoW account, the mainnet will begin with 2,048 empty blocks after the Merge block, adding padding to ensure that the chainID - a distinctive identifier to distinguish among blockchains - switches effectively and that the chain is the longest chain of ETHW.
Some engineers are perplexed by the choice to postpone the code release and wait until the very last minute to update the chainID. Roberto Bayardo, a Distinguished Software Engineer at Coinbase, submitted a GitHub pull request a few days ago on behalf of Coinbase to clarify the availability and activation of the EthereumPoW fork code. The pull request notes that a new chainID had not yet gotten submitted and that using the same chainID after the merge would significantly increase the risk of replay or double-spend attacks.
Despite the ETHW team's response to Bayardo, which said that measures are getting taken to prevent replay assaults, other users have expressed their disapproval of delaying the public publication of the code until just before the merge. GitHub user mrtestyboy781 questioned why the team did not add a function to switch the chainID terminal total difficulty is achieved and claimed that any professional organization needs time to do regression tests before running code in a production environment.