It should take 2 - 3 hours. Don't leave the berries on the cookie sheet too long before you remove them; doing so puts them at risk of getting freezer burn. Remove excess air from the bag. The more air you can remove, the less freezer burns the berries will have. Label the bags with the date you're freezing them. You can freeze berries for up to one year. Enjoy anytime.

TL;DR in Indonesian:
Masukkan loyang di dalam lemari pembeku hingga seluruh blueberry tersebut beku. Masukkan buah-buah berry yang sudah membeku ke dalam kantong kedap udara atau kantong sejenis Ziploc. Simpan kantong-kantong tersebut di dalam lemari pembeku.