Fluorescence assay

I am seeking advice on how to standardize the worm’s condition for a fluorescence assay.

I have some transgenic worms in my lab, but i am in doubt that the expression of the GFP is because of my experimental treatment, or it is already what it is when the time i seed them into 96-wells plate. (i.e the GFP intensity are already high enough)

in common sense, we do know that the expression of gene of each individual at any given time will be different,
so i’ve tried out by work picking under UV light, trying to choose the worms that “glow” almost the same, but i do not have much confidence in this.

any input will be warm welcomed. Thanks.