Here, I've set up everything that may be needed to survive not only this conflict but also whatever will come after it. I've noticed that many survivors do so as well, to some extent, and my guess is the crisis will only worsen. Especially with food, water, and fuel. Everybody wants a warm, dry shelter. I guess you're in good luck to be noticed by Sniper then. He says this night we need to try you.
Head to Customs between 21:00 and 5:00. It's recommended that you go into the raid by at least 3:00 so you have time to advance the quest before 5:00. Scavs can easily be frequently found at the crossroads, construction site, bus depot, and old gas station. Attaching a flashlight to your gun can be very helpful for hunting scavs in the darkness.