My wife's in the middle of gathering all of this together, so here's what I know:
1) Vietnamese Passport: about 14 days to 21 days to complete.
2) Police report: 10 days -but can be confusing because they don't tell you how to complete the forms correctly.
3) Passport photos with negatives: 10 days
Express Mail from Vietnam to the US: 3 days!
Advice: As soon as you finish gathering information for the I-864 package, try to get everything for the DS-230 ready.