Can't tell you when, but this is what I was told about what being put on Hold status means. (I'm in the same boat as you).
USMMA is required (by law) to offer admission to applicants based on their ranked order-of-merit by State. As candidate files are evaluated, some (whose overall standing is VERY high) are offered admission early-on, the majority, however, are placed in a "hold" status. Those candidates then wait until all applications are evaluated and rank-ordered. In the beginning of April when admissions has all completed files reviewed and sequenced, they make offers to fill the State quotas and then move to the National Waiting list. Hope this explanation helps. "Hold" status is a good thing and shows that your package was reviewed and found worthy to be competitive against others in your state....now they just have to review everyone else in your state and rank them before offers are made. It is a tireless waiting game.
Hope this helps!