Just to be sure we're talking about the same stuff, I mostly use following nomenclature:
(mnemonic) recovery words = commonly 12 or 24 words representing initial random entropy that start the BIP39 derivation
mnemonic passphrase = (optional) extension of recovery words, can be anything, commonly at least sanitized to UTF-8, IIRC, see BIP-0039 for details
OP should document very carefully and redundently analog copies of his mnemonic passphrase (and separately his recovery words, too, of course), because the smallest error in the mnemonic passphrase yields an empty wallet.
Any unique mnemonic passphrase derives an unique and therefore different wallet when added to the same set of mnemonic recovery words. There's absolutely NO margin for error with the mnemonic passphrase.
I highlight this as I've learned my lessons when I screwed up with one or two Testnet bitcoin wallets that used a less well documented mnemonic passphrase (only written hints instead of character for character; apparently I was careless because it were
only Testnet coins...

, oh well, thank the Bitcoin gods it wasn't a Mainnet wallet).
It can't be repeated often enough: always verify that you can properly recover your wallet from scratch, your analog documentation! Do not rely on digital copies, do not rely on your human memory. The latter will inevitably fail you after some time, I've first-hand experience with this, too.
It might not be well known: BIP39 always uses a mnemonic passphrase, where the default is "
mnemonic" when the mnemonic passphrase is empty, i.e. none is provided by the user.