Hello ConnyH,
from what I understand it's like this: Consider the blockchain as a path you walk down. At the moment of the fork the path splits in two paths and you can walk down BOTH paths and have the history of the original path on each path up to the moment of the fork. So deleting the blockchain part after the fork for synchronizing the BCH blockchain is one necessary measure.
The second measure you need to take is use a client, that can follow the chain down the new path. That is either Bitcoin Unlimited or Bitcoin ABC (for simplicity, take that one). You need to install one of those instead of Bitcoin Core and make Armory use that as the backend. Then the client will synchronize with the BCH chain and you will see your wallet from before the fork with your BCH coins in it.

You can't do anything wrong. BCH has a replay protection, so with the wrong signer in the transaction the transaction will not be accepted by the BCH network and vice versa. What you could do wrong: Send BCH coins to someone's BTC address or vice versa. Usually people create separate wallets for both coins in order not to confuse the addresses and the reason I will describe next. So take care, which coins the recipient expects on which address.

Possibility of losing your BCH if you wait for too long? Yes, there is a faint possibility: If the public key cryptography linking the private to the public key turns out to have a weakness or progress in quantum computing is made in the near future (likely within the next decade), so someone is able to derive your private key for an address from your public key of that address. Since you already spent coins post fork the public key for that address can be found with the spending transaction on the bitcoin blockchain. If someone were able to derive the private key from that at reasonable cost, you run the chance of losing the BCH coins in that address.