I honestly think it depends on the level of the position you seeking and for which you're qualified.  It you're talking about an hourly position, there just isn't going to be much, in any, vacation negotiation.  The same will generally be true of lower level salaried positions.  On the other hand, if you're talking a senior level position of  some sort, there probably is room to negotiate the amount of vacation included in your total compensation and benefit package.  If that's the case, I think you should settle all the other details, salary mostly, before bringing up additional time off for vacation.   My thought would be to get to the point were you can say something like, "Everything looks good to me and I'm excited about becoming a member of the team and what I know I can contribute, but before officially accepting the position, I'd like to talk about including an additional week or two of vacation in the package."  Hope this helps.

Paul W. Barada

The Negotiation Expert