Is it still possible to start an encounter unnoticed?

[Ravingdork]

Page 11 of the GMG says the following:

To determine whether someone is undetected by other participants in the encounter, you still compare their Stealth check for initiative to the Perception DC of their enemies. They’re undetected by anyone whose DC they meet or exceed. So what do you do if someone rolls better than everyone else on initiative, but all their foes beat their Perception DC? Well, all the enemies are undetected, but not unnoticed. That means the participant who rolled high still knows someone is around, and can start moving about, Seeking, and otherwise preparing to fight. The characters Avoiding Notice still have a significant advantage, since that character needs to spend actions and attempt additional checks in order to find them.

Does this mean it is impossible to start a combat encounter while retaining the unnoticed condition?

Seems to me that, that would be hard to explain away in certain scenarios.

[Garretmander]

The one time this has come up in PF2 while I was playing we went to action by action encounter mode until we decided to ambush our targets. If we had ever failed our stealth checks, that would have been our initiative rolls in that case.

Not exactly RAW, but it worked pretty well.

[Alyran]

Well, I don't think you roll initiative until someone declares an imminent intention to attack. If the group is still only planning to position around for an entire round, combat shouldn't have started yet (unless someone failed their stealth roll anyway, in which case, none of this matters).

Then the only way you don't start essentially unnoticed is if someone rolled really high perception. In which case, they should probably have at least some chance to respond to the combatants, even if they don't know their exact location.

[Ascalaphus]

I think that explanation in the GMG is written from the expectation that not everyone in the party will be using (and succeeding at) Avoid Notice. So enemies have noticed there's some people, but not necessarily you.