The product description points to three typical occasions. First: after training. The milk protein blend is intended to supply amino acids after physical activity, so the bar can be a convenient protein top-up when you are away from home and do not want a full meal.
Second: during a busy workday or travel. The bar is 60 g, requires no preparation and is easy to carry in a gym bag or backpack. It can act as a planned snack when your next proper meal is several hours away.
Third: when you want something more substantial than a biscuit but still fast. The protein and fibre content make the bar more filling than an ordinary sweet snack, so it can bridge the gap between meals. The chocolate coating and coconut taste also give it a dessert-like character, which makes it a reasonable option when a sugar craving appears and you prefer a snack with more protein and fibre than a conventional chocolate bar.
There is no single best time. It depends on your schedule. If you use it after training, treat it as a snack rather than a full meal. If you eat it between meals, it can be eaten as is. The main practical rule is to include it as part of a varied diet, not as the main source of nutrition for a meal.