When Do You Know You Are A Jedi?

Certainly : no.
Jedi (more precisely: future Jedi) do not choose to become Jedi. The Order detect them and take them from their family as they are still babies (except Anakin) in order to make them Jedi.
As far as I know, nobody has chosen to become a Jedi, and this point is central in the difference between a Jedi and a Sith because - the little I know about Sith relies on the Dark Plagueis novel that is not canon - Sith are chosen older, and asked to become Sith...
So, I assume nobody really chooses to become a Jedi : the Council chooses. The only one who excepts this is Luke who choosed the Jedi path as he was 19 and after he lost all his family and roperties in a savage attack. But at this very moment he makes the choice, don't forget Luke just intends to have a revenge upon Owen and Beru deaths, and we all know the revenge is not Jedi way

So I would say : a Jedi becomes a Jedi the day he stops being a Padawan, in other words, the day he is knighted.

 

mmmh yes, I was editing my post as you were responding I spoke about the way Luke had chosen the Jedi path, it was for revenge, and revenge is not a true Jedi idea.
What Ahsoka choosed is to stop being a Jedi, she didn't choose to become a Jedi.
So the last remaining is Anakin.... he dreamt of, but did he choose?

 

there are two levels of "being" a Jedi.

There is having the knowledge and ability of a Jedi, and being part of the orginization.

So the former - you're a Jedi when you reach a certain level in your development. No different then a martial art - you're shodan when you demonstrate that level of skill and ability. The later - you're a Jedi as long as you stay with the Jedi Order, once you leave you are no longer a Jedi - again think martial art, if you quit playing Kendo (for example) you are no longer a Kendo player.

Where it gets a little......sticky is someone like Ahsoka. While she can say "I'm not Jedi", she isn't only in sense of the later way. Ahsoka still knows how to use the force, still uses in the way the Jedi do (light, not dark etc...), she fights with Lightsabers, she opposes the Sith etc.... In every meaningful way she IS a Jedi, she just no longer has the membership card. So that same Kendo player no longer belongs to a dojo or goes to tournaments, but keeps his skills up on his own......he isn't "offical" a Kendo player but still kind of is.

 

Exactly. When Darth Vader tells her "Revenge is not the Jedi way" when she says she will avenge her former master, she replies that but for me it is like she abandoned the Jedi order because she got disillusioned but did she stop actually following the path of the Light side of the Force? Maybe in a unorthodox way - like we read from her in the "Ahsoka" book, but she keeps committed to the Light, mostly.

 

This is why I don't buy the "Ahsoka is still alive during the OT, and they say Luke is the last Jedi because Ahsoka isn't a Jedi", weak sauce arguments.