Aha! The Encyclopedia begins to prove its usefulness! Here is the answer to my question about how long Academy training lasts:
“There are two options when joining the TSN; join as enlisted personnel, or as an officer. Most new recruits join as enlisted personnel, taking on a particular trade within the TSN. Enlisted personnel are put through a basic training programme, after which they join other TSN enlisted in an apprenticeship-style scheme, training on the job.
Those who join as officers complete a basic training programme, alongside those who joined as enlisted personnel. After this basic training programme, they are then sent to the TSN Academy for between 2 and 4 years to continue their officer training. Officers then leave the academy with the rank of Cadet, and complete their final stage of their training on active duty. When an officer is promoted to Ensign, it signifies they have officially completed the training for officer and are regarded as full officers serving in the TSN.”