The best time to buy it is when the price is going down, then sell it when the price is going up.

For example:

• On 18 Feb 2019, you bought 1 gram of gold when the price is at Rp615.759/gram.
• On 18 Feb 2020, the price rose by around 16.9% to Rp719,865/gram.
• See the profit right there? You get +Rp104.106.