QUOTE(Poiteen @ Apr 29 2008, 10:19 AM)

I think I've said this to you before, but in your case, I would include a covering letter with the RFE, and ask if they might delay issuing the Approval of the I-130 for a few months. The London Embassy seem to be very understanding of peoples situations, and I'm sure would respond favourable to this kind of request.
If they must issue the approval soon, then it is my understanding (someone jump in if i'm wrong) that the approval of the petition is good for a year. Meaning that the visa must be issued withing a year of the approval of the petition. So even if you delayed the visa issuance till next, say, February, you would still have 6 months validity on the visa before you must enter the country. And probably another few months of leeway to go over and back tying up loose ends.
Basically there is no way that you'll be able to delay the process enough yourself to avoid having the visa issued sometime this year. The best thing to do is include a letter with the RFE explaining the situation, maybe they'll agree to delay issuing the NOA2 or Packet 3 until you let them know that you're ready.
Yes, the approved I-130 is good for a year. I don't see why they're going to have a problem. The approval will probably be sometime in May, which means they can comfortably delay return of packet 3 to Jan 08 or so and then say the interview happens in Feb/March, then they have until July/August of 2009 to use the visa. My suggestion would be to send a letter at some point over the summer saying they have received packet 3 but as they do not want to move to the US until April of 2009, they will not be returning the DS-230 Part1 and checklist until January 09 with the understanding that the I-130 approval is good for one year. I would think that asking for a delay on issuing the I-130 would cause confusion, but that is based on my sense of it rather than actually hearing about anyone's experience with trying it.