Hello, Nathan!
When using your MagicBand to make purchases using a previously linked credit or debit card, your card will be charged after you check out from your Walt Disney World Resort hotel. If you would like to check your total charges before you check out, you may request a transaction history at your hotel's front desk. There is a limit to how much you can charge to your MagicBand. Recently that amount has been set to $1,500 for Guests staying at Value and Moderate level resort hotels and $2,500 for Guests staying at Deluxe level resort hotels. Keep in mind that these limits may change in the future, so be sure to check with the front desk at your hotel.
Working at a financial institution, I do have a bit of advice if you plan on linking a debit card. Contact your financial institution prior to your arrival and inquire if your debit card has a daily spending limit and what the limit is. For example, if your financial institution only allows $1,000 in debit card purchases per day and you charge more during your stay, even though you are making the purchases over the course of several days, your entire total will be put through on one day and may cause problems. If your financial institution has such limits it may be best to link a credit card instead of your debit card, or you may ask the front desk at your resort to put through the charges a few times during your stay instead of waiting until you check out.
Wishing you and your family a magical vacation, Nathan!
~Rachel