You can leave them on for 18/6 or 24/0 whichever one you want really. I tend to leave them on 24/0 for the first 2 -3 weeks then switch over to 18/6 and I have no idea why really. My current grow I am going to do 24/0 all through veg.
Some people say the benifits of 24/0 is that a plant does not need a dark cycle and constantly grows because of the light.
Other people say the benefits of the 18/6 is that the plant naturally is use to a dark cycle and is therefore needed.
So pick one of those and stick with it lol, I'm somewhere in-between.
I would say 85f is an okay temp it is on the high side though... I wouldn't let it go any higher than that. But as long as there some humidity as well I'm sure they will be fine
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Oops just re-read and saw it says for germination... if you mean the seed hasn't broke the surface yet then you don't need any light, until the roots start to show and the cotyledon are also showing... then follow the above