In what order does roblox load game instances?

[grif_0 (not_grif)]

To my knowledge, ReplicatedFirst is the first thing that loads into your game. This would be useful for any loading screens you make. The next thing that loads in are your LocalScripts, which is why you always want to WaitForChild in them.

Changes to Non-ReplicatedFirst Loading Order

Hi Developers, There are some changes coming to the non-ReplicatedFirst loading order that we want to walk you through before they go live. ReplicatedFirst exists as a means for game creators to create loading screens and otherwise manage and optimize game loading. The order and timing of the arrival of the rest of the instances is not guaranteed, so it is expected for developers to use WaitForChild to determine when parts of the game have loaded. If you want to read more about best practices…

This post also explains more about the loading order.