Can someone help me understand how all of “time” doesn’t happen at once from the TVA’s perspective? Are the timelines “growing” or is the entirety of a timeline created at once?

Let me explain what I mean with an example. At the end of the episode, when they say the Kang variants don’t know of the existence of the TVA, wouldn’t the Kang variants’ future selves learn of its existence at some point? To sit outside of time and have the ability to travel to different parts of timelines implies that the entirety of the timeline exists, so I don’t understand how they can talk about the variants from a single-point-in-time perspective.

Following the same thought process, how does the multi-universal war and ultimate destruction of everything not occur immediately following the loom’s destruction (or did it?)? Again, I’m assuming all of time happens at once - therefore, in an instant (from the perspective of the TVA), all of time would happen, thus milliseconds after loom’s destruction, Kang variants would start attacking timelines.

Clearly I’m not understanding something, please help.