Maybe a stupid question? Are these “pre-stretched”. They came with my new SLX 10sp shifters.
I’m going on a big bike trip over several days soon. I am planning on installing new cables before the ride. Should I install them a week before and let them settle in and stretch. Or will they be good to go if I put them on a day before the ride?
Thanks for any advice.

Just install them whenever you want. If they do settle in then use the barrel adjusters to dial it out. No big deal.

Or when you do install them, before you tighten it up with the bolt on the mech, hold the cable and cycle through the gears a good few times and that will stretch the cable in the same manner as actually using the gears.