From http://www.usembassy.org.uk/cons_new/visa/iv/immrel.html :


Note: If the U.S. citizen and immigrant visa applicant reside in the United Kingdom and the U.S. citizen is filing the I-130 with the Department of Homeland Security (Immigration) in London, it will be possible to begin the administrative processing of the immigrant visa application before the petition is approved and received by the Immigrant Visa Unit.

What exactly does this mean? Can I be filling out the DS-230 now and sending it?

Also, on the DS-230, question #10 wants the permanent address of where we intend to live. Do I just fill in where we'll be staying temporarily (my sister's address?). We won't have a "permanent" address until we've been there awhile...

Thanks for any help!!

It does seem to mean that you can submit your IV application docs now, before your I-130 is approved. We had a discussion about this not too long ago in this forum..

Even if you do not submit them immediately, it's not a bad idea for you to have ALL your P3 documents ready (visa app, police cert etc) so that as soon as you hear from the Consulate, you can tell them 'we're ready!'.

You can find all the forms online, and gather the other required documents before your I-130 is approved. Turning them in early or not is up to you.