I understand the concern of wreaking havoc on the duration of spells and other effects by delaying your turn at will in the initiative order, hence why it's not possible to "change your place" once you are engaged in an encounter.
However, in a game I played yesterday, something happened that made me think: my character was sleeping at the start of an encounter (a night ambush), and so the DM only made me roll initiative when another character woke mine up.
What I'm wondering is whether it's possible for a creature to willingly delay entering an encounter that they can see, in order to roll initiative later than the other involved creatures, thus not changing its initiative position, just being added later. Is such a thing possible per RAW?
Technically speaking, it's not that different from seeing a fight between two distant NPCs and choosing not to get involved right away, but instead picking the right moment to do so (and rolling initiative at that point). But contrary to this question (where the character just arrives later and rolls initiative right when he sees the encounter), I specifically want to know whether you can see an encounter but choose not to roll initiative just yet, essentially delaying your participation in the encounter until a later time.