Zur's right, level 7 is a solid point to head to the Tower. Same for the rest of the expansion, it's all on roughly the same difficulty level.
The main requirement for the Tower, though, is your ability to find and disarm traps. As long as you can reach ~90 Find/Disarm, you can go earlier for more of a combat challenge. There are tons of traps in that place, and not being able to handle them is a frustrating and impassible obstacle for a low-level party. The combat should be managable, if difficult, at a lower level; You'll be getting powerful loot, including plenty of wands, potions, and scrolls to make up for lack of experience points.
my post was only max exp vs max level i don't know what is the optimal level because it varies from player's experience in the game and other meta-things
Comments
bg1 exp limit was 89k
89k is
7lvl fighter
8lvl mage
7lvlcleric
8lvl thief
8lvl druid
i was pobably wrong in somethng but most shoulkd be ok
The main requirement for the Tower, though, is your ability to find and disarm traps. As long as you can reach ~90 Find/Disarm, you can go earlier for more of a combat challenge. There are tons of traps in that place, and not being able to handle them is a frustrating and impassible obstacle for a low-level party. The combat should be managable, if difficult, at a lower level; You'll be getting powerful loot, including plenty of wands, potions, and scrolls to make up for lack of experience points.