Not to disagree with Victrina; she's right, but when you state "trim candles", are you referring to breaking candles that are still extending, where the needles aren't exposed yet, or removing this year's candles whose needles are fully open and away from the candle?
Several outcomes are possible from "trimming" candles, depending on where they are in their development:
A. If needles are still concealed in the sheath, breaking part of the candle now to equalize lengths would be ok...although that may suggest your pine is very slow in growing...don't know where you are.
B. If needles are open and away from the candle, breaking part of the candle now may result in advantageous growth at the base of this year's candle, and will set buds for next year between the individual needles on this year's growth. It will prevent buds from forming on the tips, and cause unpredictable growth. Probably not the best course of action.
C. If the needles are open and away from the candle, removing all of this year's candle is called "Candle Pruning", and it will cause new growth at the base of each of the cuts. If this is the case, this is the operation that is described as done in phases; current year's weak (lower, interior, generally) candles are removed to their base, wait a week and remove the stronger candles, wait a week and remove the strongest candles. Depending on where you live, this may be the right time. It takes about 100 days to regenerate after this process is begun; so count backwards from your average first frost and you'll know when to begin. Here, it's around the 4th of July.
Here is a pictoral of this process over several years on one of my pines, it illustrates the process well.