If they want to save a lot of money they should not have physical conventions. Just broadcast the convention at jw.org- and have the new releases sent to the congs the beginning of June.
Then everyone can watch the program from home (or at the kh if they don't have the internet) and they can save on traveling expenses etc and the society won't have to rent and clean the facilities.
The new publications can be made available at the kh beginning in early June or late May.
And hopefully I could still obtain copies without going to the meetings.