Along participation at the Olympic Games since 1952, Team Indonesia achieved the first medal (silver) in Seoul, 1988, from Archery. It took 36 years to wait. Four years later, the first gold medal was presented by Susi Susanti in 1992 Barcelona Olympic and followed by her future husband, Alan Budi Kusuma, with another gold medal.
From the graph below, the most medals earned was in 2000 Sydney Olympic with 6 medals in total. While in the latest 2016 Rio Olympic, Indonesia only achieved 3 medals. Although it was not the best achievement, at least the rank at Rio Olympic was 17 ranks better than 2012 London Olympic.
Source: https://en.wikipedia.org/wiki/Indonesia_at_the_Olympics