Wait for the second light in the 3-2-1 countdown to turn on, then press and hold A to gain an initial speed advantage.

In Mario Kart 8 Deluxe , use A to accelerate, B to brake/reverse, L to use items, and ZR to hop for mini-turbos. 🔓 Unlocking Content

Mario Kart 8 Deluxe: Prima Official Guide - Softcover - AbeBooks