When to turn on UVA-30 bar?

[Autotron]

I recently got a refurb HLG-650R for my 4x4 along with the UV light bar to attach to it. I know the recommendation is to use the UV bar only during flower. My question is, when is the right time to turn it on during flower? My concern is that if I turn it on too early in the flower cycle, it may cause some stress and induce hermaphrodite flowers on my female plants. Is this a valid concern? Is it safe to use right after the stretch or should I wait until mid-flower or later to reduce the risk of getting seeds from hermies?

@Les @HLG

 

[Trichome farmer]

I recently got a refurb HLG-650R for my 4x4 along with the UV light bar to attach to it. I know the recommendation is to use the UV bar only during flower. My question is, when is the right time to turn it on during flower? My concern is that if I turn it on too early in the flower cycle, it may cause some stress and induce hermaphrodite flowers on my female plants. Is this a valid concern? Is it safe to use right after the stretch or should I wait until mid-flower or later to reduce the risk of getting seeds from hermies?

@Les @HLG

for the last two weeks of flower turn it on for 2 hours in the middle of the light cycle this is what iv been told is best and iv had only positive effects