Keep an eye on this link
https://data.cityofnewyork.us/City-Government/Bus-Operator-Conductor-Track-Worker-Certifications/pjqi-8psc
Whenever Transit requests a batch of candidates for Track, we'll know from this site. We'll be able to see how many vacancies and how many names they pulled.
We should see a batch of names being pulled within the next few weeks in my opinion. Depending on the amount of vacancies and so forth, keep in mind there hasn't been a class since September 2018, so whoever fired/retired/quit/promoted and or got demoted between now and then, they haven't been replaced.