IIRC, it's not a moratorium on trades during draft day. It's a deadline for when a traded pick will be announced as the new team's pick. And I think it's 4 hours before.
For instance, if right now we traded the 6 pick for the 2, then Stern would announce "With the 2nd pick, the Portland Trail Blazers select..."
If we traded right before the draft (b/c CHA didn't get any better offers), then it would be "With the 2nd pick, the Charlotte Bobcats select (Portland's choice)". Bucher and everyone would then say "This pick has been agreed to trade to Portland for X" but the guy will put on the CHA ballcap/jersey/etc. Then at the end of the first round they can start announcing trades in order of league approval.