If you cant get a good closeup of your trichomes, yhe easiest way to know when harvest time has come is when the calyxes stop producing new ones and all the older ones are shriveled up.
You see on the right side of this image there are still white calyx hairs? And the older ines are brown and shriveled? This bud is getting close. Once the white hairs are no longer being produced, you can be fairly confident the bud is mature.
Perfect example here, a lot of trichomes, however, there is still white hairs being born. If I harvest now, I will lose bud volume as the calyxes have yet to swell. I will also not have as much trichomes because the collect on the swollen calyxes. Then we need to give a few days for the trichomes to mature.