I emailed the pilot service center and this is the response I got:

"When you are returning from Military Leave, you would advise the Pilot Service Center via an email with your available date for training. If you can give 10 days notice that would be good because you will have to clear security, background check, drug test and Medical before training.

You will be provided a list of vacancies of which you will be able to bid for
according to your seniority.

If you have further questions or concerns, please contact the Pilot Service
Center.

Thank you."