Is it a bad idea to let it sit longer than 8 hours? I’m looking to put it together before work, but then it wouldn’t be another ten hours before I...

Depends how you feel about raw garlic. It's kind of an edgy ingredient to begin with, and will grow stronger (and some would say fouler) with time. I'd guess that the basil will be OK if well coated with oil, but I wouldn't bet the farm on it.

Will be fine to let sit ten hrs and then proceed with the recipe to make the pasta. I think longer than 12 would be a bad idea though.
The directions have you add the basil and then let it sit but it will discolor to a dark unattractive shade (perfectly safe to eat), i would wait and add the basil just before serving