Well, the reason I linked that thread is because it could potentially answer your question. Anyway, let me just refer to the mana formula given in that thread.
For your case, R = 10 (as Li Xiu is average speed), MB = 5% (from costume) + 9% (from L11 troop) + 2% (emblem node) + 24% (Khagan mana boost) = 40%
Then, using Eq (2) we have, P x (100+40) = 10 x 100 => P = 7.14 ~ 8 tiles
Which means, even with the Khagan mana boost she will still need 8 tiles to charge fully. If you actually want her to charge in 7 tiles (that is P = 7) you would need a mana boost of 7 x (100 + MB) = 1000 or, MB = 42.8 ~ 43%. So in order to achieve this, you would need L23 mana troop (13%) instead of the L11 troop, along with all the other boosts. Hope this helps. 