How long does a balance transfer payment take?

Do you mean transferring from Apple Cash to your bank account. If so, the free transfer is expected to take 1-3 business days. That means you cannot count Saturday or Sunday.

Transfer money in Apple Cash to your bank account or debit card - Apple Support

It is a little confusing because you posted in the Apple Card forum which is a credit card and not able do any balance transfers. I don't know if you are referring to paying off your Apple Card balance or something else. Additional details may be necessary if the solution provided above is not what you were looking for.

Please be aware Friday is a federal banking holiday and funds will not move or be deposited during a holiday. This also applies to weekends as most banks won’t complete transfers and make funds available until the next business day, which is Monday the 22nd, a full week from today.