Using the EAA "Step-by-Step Certification Guide", I applied for my reserved "N" number, N531X. I would have preferred N541X (54 being my kit serial number) but it was not available. I hope kit owner #53 didn't have the number in mind.
Completed forms 8050-1, Aircraft Registration Application; 8050-2, Kit Bill of Sale (w/duplicate); 8050-88, Affidavit of Ownership for Amateur-Built and other non-type Certificated Aircraft (notarized), and fees for assignment of special N-number ($10) and aircraft registration ($5). I was carefull to use the exact same name format on all the forms. Made a copy of all the docs and sent the package to the FAA by USPS Priority Mail so I have delivery confirmation.
The N-number registration needs to be in hand prior the airworthiness inspection (which requires several other forms). Getting the N-number in hand could take several weeks. When I get an airworthiness certificate I'll need to apply for a State registration.