Getting the FAA Registration done was a lengthy process. I’ll give you a couple of tips to avoid wasting time. In short this process took me 2 months but it could have been done in 3 weeks if I did it again. Communication with the FAA was slow and the online submission actually made things more complicated and slower. 
Tips:
1. Get this EAA publication entitled “Homebuilders Step-by-Step Certification Guide”. It is extremely helpful.
2. You can use the FAA Cares system to submit the docs online. However, you won’t get a response online and you still need to mail in the docs. They sent me a letter that took weeks to receive that asked me to mail them hard copy docs. So online submission was not really useful.
3. You need one or more bills of sale for your kit. I needed two, one from Searey and one from the reseller I bought the kit from. Searey didn’t provide bills of sale originally, they expected you to ask for it later when finished building. It seems that they are not currently in business. Fortunately I bought via a reseller who provided me with two things
1. His bill of sale to me
2. an affidavit that Searey was out of business in place of their bill of sale
That was acceptable to the FAA.
