You can only claim an endorsement after a period of earning taxable income from that endorsement.
There is a case similar regarding an employee who resigned from a position conducted training for a higher position within his profession and then was re-employed. He tried to claim the expense of the training and was denied as it occured before he was employed by his current employer. That is the training was not deemed to be improving his existing employment.
Another example given by the tax office is a flight engineer who claimed tax deductions training for a PPL whilst employed at an airline as a flight engineer. It was deemed the training improved his current proffesional status at the company and was allowed.
The big issue is whether you are employed or not at the time the training took place. If you were you can claim it against the tax paid whilst employed by that firm. If you were not employed at the time no tax benefit can be gained as you were not earning taxable income at the time.