You may be surprised... all depends which courier they use.
If it's UPS they are VERY efficient, we use them in our business as they are the best, so you could we wearing it to the party on Saturday.
The amount charged for the postage should give you an idea how it's being dispatched NEXT DAY, is the most expensive, 48 hours, 24 hours are usually a bit less and usual postal delivery cheaper still, that will be the slowest, but now the Christmas rush is over, you may be lucky.
Good Luck!