Only one in six of the roughly 12,000 workers expected at the plant have been hired so far, in part because Tesla is still awaiting final approval from local authorities to begin production. The council will consist of 19 members.
IG Metall, which represents workers across automotive companies as well as other industrial sectors, fear that calling an election before a wider swathe of workers are hired will lead to a council top-heavy with management.
Under German labour law, only employees who have been working at a company for at least six months can stand for election.
The results of the election will be valid regardless of what proportion of the workforce votes, and a new election can only be called after two years if the workforce has grown by more than 50%.
"Those hired so far do not represent the workforce as it will look when production begins or reaches full capacity," said Birgit Dietze, head of IG Metall's regional office for Berlin-Brandenburg-Saxony, where Tesla's factory is located
Her comment echoed statements she made in November, when the union established that an election was on the cards.
A Tesla representative was not immediately available for comment.
Chief Executive Elon Musk has sparred with organised labour in the past and was ordered in March last year to delete a comment made on Twitter in 2018, which threatened to strip U.S. employees of their stock options if they formed a union.
(Corrects 5th paragraph to say new election can be called in 2 years if workforce has grown by more than 50%, not when it has more than doubled)
(Reporting by Victoria Waldersee and Ilona Wissenbach; Additional reporting by Nadine Schimroszik; Editing by Miranda Murray and David Goodman)