Frontier has confirmed that Planet Zoo 2 launches on October 13 at 15:00 BST, equivalent to 14:00 UTC. Steam customers who pre-purchase the game will be able to preload it.
The team is aiming to make Steam preloading available from October 12 at 15:00 BST, also 14:00 UTC. That is a target availability time rather than a guarantee that every download starts at the exact minute. Preloading provides game files in advance; it does not move the playable launch ahead of October 13. The confirmation specifically concerns Steam pre-purchases and gives no equivalent schedule for other storefronts. The announcement also mentions a Bonus Content Pack for pre-purchasing. Check the time zone conversion when planning your first session.
Sources and checks
Planet Zoo 2 | Release Timing! · Steam