How do I make it so the game starts with less than 8 players

[Edge100x]

You can adjust "Round start player count" as low as 1 on the easy setup page here, and at the same time change "Preround start player count" to something lower, such as 0. However, keep in mind that a number under 8 will remove you from "quick match" eligibility, so you'll see fewer random public players.