Turnaround time on parts varies, depending on what kind of part it is. Routine stuff ships out pretty quickly, but since most vendors use inexpensive shipping which often takes 7-10 days, turnaround once a part is ordered can routinely be 2 weeks.
Some parts, like cabinet doors, have to be custom ordered from the part of the factory that builds them. That can add a week or two.
And of course, the dealer may not have placed the parts order right away. If you want to find out what's going on, call Heartland Customer Service at 877-262-8032. Have your VIN # ready. They can tell you what the dealer has on order from them and what the status of the order is.
Also keep in mind that dealers don't necessarily work on your rig right when you drop it off. If they're busy, it may wait a week or two. Same thing can happen when the parts show up. It may sit until the tech gets to it. You can manage this to a degree by setting expectations when you bring it in. If you need fast turnaround, tell them you're willing to pay for expedited shipping (which can be expensive). But if you do so, also ask them to work on it right away to diagnose, and again to repair.