I am beginning to hang my recessed light housings (not remodel but new
work).

I laid out the desired spacing and location in CAD, and when it comes time
to install, I ran into a few challenges. Right now I am struggling with a
set of 9 lights.

I put in the first, second, and when it comes to the third, the joist is
right in the middle of where I want the light to be, so it won't work.
Which means if I want the light to be spaced the same, I need to move the
second light. I can slide it along the flange, but if it's already butt up
against the joist then I can't slide it. Furthermore, by sliding the second
light, the other two rows will need adjustments as well. Basically, to run
into trouble positioning one light, there is impact on the positions of many
others. I have nine in the living room, eight in the dinning room, and six
in the kitchen and since it's all open, they are all aligned with each
other, so I decided I will need to plan it out better before I start hanging
the lights.

So what I am looking for is tips on what the best way to hang them. I
started to mark them down on the floor, since there is no way to mark them
on the ceiling (ceiling sheet rock is down). Now when I start to hang them,
how do I align where it is on the floor to the location on the ceiling? Do
I use a plumb-bob?

Even though the ceiling is down, the fiber glass insulation is still there.
I need to trim the insulation back a few inches since what I got are Non-IC
housings. What is the best way to trim them? A pair of scissors? or just
rip them apart?

Another question is what if some insulation get too close would that start a
fire? These are fiberglass insulation I think they are highly flammable.

Last question is once I have all the housings wired, in order to test them,
can I screw the bulbs in without putting in the trim first - just to test?

Thanks,

MC