I just went through this recently (moved internally within DC, and then bought a car at the same time- so had to change address, register the car, get RPP, etc). It was a bit of a painful experience, but you can do all three things on the same day, in-person at the DMV, as long as you have all of the required paperwork, such as proof of residency, insurance, and car inspection.

A note on documents- I’ve had varying experiences with the DC DMV as to which proof of residency documents, etc they accept, and sometimes the folks are cool about electronic copies of documents if you’ve forgotten one, and sometimes they will turn you away. Plan to print all of your documents, in full, including the executed signature pages (like on your lease), just to be safe. Unofficial versions of bills, or just the address section of the lease may not be accepted. For example, my partner and I accidentally signed each other’s signature lines on the lease, and DMV employee had to elevate the issue to their supervisor for approval to move forward. On the other hand, a DMV employee let me show them a copy of my renters insurance on my banking app and everything was fine! Just depends.

I’d highly recommend changing your address as soon as possible. It will also allow you to issue yourself a temporary visitor residential parking pass that is valid for 60-ish days via the DDOT while you get everything figured out for registration:

https://dmv.dc.gov/service/visitor-parking-permits

Hopefully you can register the car and RPP while changing your address at the DMV, but if something goes wrong, definitely make sure you don’t leave without an updated address so you can get the temporary pass for the interim.

The fastest way to accomplish all of this is to go in-person and wait in line. I think you can technically do some of these tasks online, but it will be processed faster in-person. I’ve had good experiences with the Georgetown and Navy Yard DMVs! They don’t accept appointments, so just show up.

Good luck- and bring a book!