3. If during that time you get replayed, go back to step one. You still have access to all of your coins since you own the private key.
It is not a matter of "if". It will undoubtedly happen as long as the transaction is valid on both chains, so as soon as you broadcast one transaction on one chain it will instantly get relayed on to the other.
There are better "replay protections" than yours, just read the forums.