You've got your answer but I just want to add that this is not a safe way to back up your wallet seed.
It's true that you only need know the first 4 letters to identify a bip39 word but to recover your wallet you need to have saved those letters correctly.
Let's assume one of the seed words is "present", the first 4 letters are "pres". If you mistakenly save it as "pris", you'll end up with a totally different word when you recover your wallet which is "prison"!
I agree that this is not the way to safely store a key phrase, and this is because of the words similarity. While the first 4 letter of the word might be enough to identify the word you can't recover the key phrase if those 4 letters for each word are not correct.
So makes no sense to correctly write the first 4 letters of each word and then use this system when you might as well copy correctly the full words.
This is mainly advice for new people looking to secure their crypto assets as too often you find that the seed phrase was not written down (or stored in any way) and lost their funds.