Mold can ONLY be used after you finish the whole cultivation..using a fairy doesnt matter in this case, you will need to finish the quests. after using the mold u will be auto celestial sage without needing the completion of more quests.
when u did it ? cuz it doesnt work anymore :p u r free to try it
Agatio said it never worked afaik but he can clarify it lolsince i never used one :x but i see people having problems with it, like dailly :x