According to @TwoEpicBuddies on Twitter, they have found the actual path that the cube will take in Fortnite until it stops in Loot Lake!
Leaked: The path will the cube in Fortnite Battle Royale
Snippet of codes found on in-games file showed that the cube would move around the map and leave 7 runes. So far, the cube has left 4 runes so there’s still 3 left. According to the in-games files that the leakers have found, the cube will to just outside Retail Row then move up to Wailing woods, then cross to Lazy Links and then across to Pleasant Park before stopping at Loot Lake just outside Tilted Towers.