WDW Florist does NOT deliver to any resort rooms. Any flowers or gift baskets you order from them will be delivered to the Front Desk of the Disney resort. Then depending on the item (such as alcohol cannot be left) the Runner for the resort will deliver the item to the room. The Runner generally will not deliver to the room before guest checks in, the exception being Club Level rooms and Suites. This is to ensure that the guest is actually already inhoused to the room.
If you order for friends, you can be sure if you follow up by calling the resort after you think that the item has been delivered from the florist. But the resorts do this every day, all day, so there is unlikely to be a problem.
Also the guest may not have a Privacy sign on the door, or it will not be left. They will need to pick it up at the Front Desk. That is a major reason that flowers or gift baskets do not make it on time for birthdays, anniversaries, etc. The runner tries to make a delivery and the Privacy sign is on the door.