Best time during light cycle to harvest?

Is it better to snip the stem at any point during the day cycle for best results, or is that getting too particular?

It's good to harvest in the morning when the plant's trichome potency is at its' peak. The plant builds up THC resins during the night time and it acts as a type of sunblock to protect the plant during the day. Thus is why some say it's good to give the plants a 72 hour photoperiod before harvest to allow for maximum THC levels.