I ordered something from an out of state non-Jewish store, and they ship with FedEx. It leaves Wednesday, and according to the seller, “The delivery times are usually very accurate. They expect to get it to your house on Saturday afternoon.” If given that Shabbos now ends at 5:20 PM, can we say that since it might arrive later, it’s not a problem, or it can’t/shouldn’t be done?
If you didn’t specify that you want it to come, in a way that they would have to work on shabbos to get it to you, then it is permitted. This is because the was hired to get the job done, not to specifically do it on shabbos, therefore it is considered as if they are doing it for their own work convenience, and not specifically on shabbos for you.
O:CH 244-5, Shmiras Shabbos Khilchoso 30 ftnt 23..