Been through too many documentations. You can either choose to do it yourself or pay an agency to do it for you. It is advised to use an agency as they will do it all for you including the title searches and bill of sale findings. The last one we did took almost 9 months but that is extremely unusual. Most of the time it is about 4-6 weeks, if all the paperwork is in order. You still have to list the boat with the state of principal use and for tax purposes (if you really want to) but you do not use the state numbers on the bow anymore. It is advised for larger boats and especially those going out to sea. It also registers the boat with the Coast Guard for helping in any tracking or recovery. We have also learned that most banks financing boats over $100K will require it to be documented.
We are about to document our newest boat here shortly. We use Atlantic Documentation here I don't know who is available in your area.
I hope this helps a little. PM us if you want more details.
Bill / Patti