Since then, he's grown from 130 kilograms to 580 kilograms and his keepers say he's hit most growth milestones, including the development of permanent tusks.
Senior elephant keeper Lucy Melo says staff are particularly impressed by his intelligence.
"He is an incredibly fast learner who doesn't make mistakes in his behaviour and training, so given his intelligence we know to start planning for more complex stimulation as he grows into a young bull," she said on Friday.
The calf was treated to a celebratory meal, with the food arranged in the shape of a number one.
Jai Dee, whose name means "good heart" in Thai, was the 10th elephant born in the past 11 years under a regional conservation breeding program for Asian elephants in Australia.
He was also the second calf for Pak Poon, who had a female calf in November 2010 named Tukta.
Ms Melo says he's becoming a more confident swimmer and his family is more relaxed about letting him in the water.
The only skill he's yet to master for a calf of his age is trumpeting, despite making other vocalisations.