According to the search results, the recommended level for entering Act 3 of Baldurs Gate 3 is around level 9. However, it is important to note that leveling up is relatively fast in Act 3, so if you are slightly underleveled, you can try to avoid hard fights and complete other quests for easy levels. Additionally, Act 3 enemies grant a massive amount of XP when slain, so it is possible to reach the level cap within a few hours of starting Act 3. Therefore, it is recommended to complete most of the side quests available to reach level 12, which is the level cap, and focus on obtaining better items.