Hold the conference in March
The majority of our data stewards are off between the end of June and end of August. This would be 60-70% of our participants.
Our district / vendor conferences are held in October, November, December and April.
Our conferences should take place prior to the vendor events as their systems should be reflecting our changes when appropriate.
Chris Plansky commented
March would be good, as long as it does not conflict with the Brainstorm conference for IT people.