When is the right time to switch main from Weiyan to Han Sui?

http://wan.renren.com/bbs/thread-859476-1-2.html

Its written above :)

Basically you need to beat Cao Cao after God Zhang Fei #2, clear up till Jade 7-24 first. This is advice from China.

But 1 thing sure is before God Zhang Fei#2, dun switch. The God ZF#2 NPC is in the middle and you can only use Taper and Echelon form to clear. With EVA form you cannot use Han Sui. Hence only with Echelon form which probably not so suitable...