How can you have so many candies but no good ttar yet? and what's bad about an 89% 14att ttar?
having high lvl/cp ttars helps, and with so many candies it doesn't hurt so much to evolve and see what you get, but the investment of tm's if u get the wrong moveset is then something to consider as well.
To me personally, it would prolly be replaced eventually for a better IV ttar of the same lvl, but given the rarity of larvitars (even during event I only see them every so often), that would maybe still be a while.
So ehm, if you have the TM's to use in case of a bad moveset, i'd say go for it!