Evolve Trapinch?

Why are you asking this when you don't have enough candy to evolve the Trapinch in the first place? Evolving from Trapinch to Flygon requires you to have a minimum of 124 candy.

Re-evaluate when you have the candy. No reason to make any decisions before then.

Wait for Trapinch Community Day.

Good for you. Feels like I get 60-70% Trapinch from my 10 km eggs. Just evolve one and forget about that Pokémon.

I'd hold onto it, would get a CD, not likely but its possible.

Also with Earth power in the code, flygon could get a boost in use if its a satisfactory move and flygon gets access to it. I'd hold off doing anything right now, be it power up or evolve really any pokemon (which the exception of mass evolving evo fodder, or powering up an SB mewtwo) because of the CP rebalance coming/gen IV release

As soon as I evolved my best IV Trapinch, I hatched a perfect.