Japanese Black Pine repot

[Haidr]

Hi all, Hi@Shibui, Need advice on repotting my black pine bonsai. The tree is healthy overall but the soil is compacted and heavily organic. What is the best time to repot? What soil mix should I use? Location is Melbourne, Australia. Currently mid/end winter. Temperature ranges from 5-15 degrees C (41-59 degrees fahrenheit)
Root pictures from December 2024
Pictures of the bonsai are current