Call, email, send smoke signals, do what ever it takes to let them know you will take the EMB class, or what ever is offered first. You don't earn any more on the jet the first year. And if you want to upgrade on the Bro you won't be intimidated, like so many are, to toss your hat in the ring.

The sooner you start the sooner your place in line is held (read: seniority number!)