The ideal is to get all your top JV partners only promoting your product in any given launch week.
If you cannot get that, then the next best thing to aim for is to get as many of them as possible to promote for you in the same week as maybe they're already promoting someone else. Needs to be at least 2 days apart. i.e. Monday & Wednesday or Tues / Thurs. If your partners are promoting someone else on a Tuesday they're unlikely to mail for you the following day, but may be two days later.