I don't think you'll hear anything until a week or two from now. It started with only 7, then 11, now it's at 12, but they're trying to get approval for 15. So that's what Management are waiting for. All they need is the bean counter to say "sure, 15 sounds good.".
Who knows at this point. The rumoured number keeps bouncing around. If it is 20, I would imagine they would want two classes as trainers are in short supply.
Regardless, the delay hurts the new hires. They will no doubt miss the 2019 bid. None will likely get signed off this year. Lines are proffered up as new hires get upgraded so the longer it takes to get upgraded, the worse schedule you will get for whatever is left of 2019.
We need these new hires and more to open more desks to reduce the domestic workload. However, this hiring is supposed to be for projected retirements. There are well over a hundred dispatchers near or exceeding the 30 year mark in the company. The JCBA contract rates and work rules are pushing retirements back as those dispatchers look to pad their retirement and enjoy a pretty good schedule with less than 6 months of working days per year after vacation or they can pick up a lot of double time every month for massive paychecks.
Eventually over the next five years or so, many will likely retire. In the past, the company waited until the retirements occurred and hired a whole bunch all at once. There are some issues with doing that and this hiring is meant to spread things out. Of course the bean counters aren't big on having people on the payroll that are there to wait for retirements to occur. This is why the hiring process is taking so long as management irons out what they want to do.