Is there a difference between the dekiteru/dekita part in "Junbi wa dekiteru/dekita",and ii in "junbi wa ii"?

Question

I would like to know if, like:

Junbi wa ii

Junbi wa dekiteru

Junbi wa dekita

Are all interchangeable? I feel like the last two mean "Plans are complete" and "Plans have been completed" respectfully, but the first one, does it just mean "Plans are good", but i'd like to be sure. Also are there any nuances? Are they all used in the same situations?

Thanks!

Answer 1

All those sentences can be question ("Ready?") or predicative ("Ready.").

• 準備はいい (junbi wa ii)
  • Q: lit. "(Are you) well-prepared?" ~ "Are you ready?"
  • P: lit. "(I am) indeed well-prepared."

This one is based on an idiom 準備がいい "well-prepared". If you use the exact phrase in question, it becomes almost equivalent to English "Are you ready?", or "Have you done all the job before the next action?" As a normal statement, however, it's neither idiomatic nor frequently used.

• 準備はできてる (junbi wa dekiteru)
  • Q: lit. "Has the preparation already finished?" ~ "Are you ready?"
  • P: lit. "The preparation has already finished." ~ "I'm (already) ready."

～てる < ている is usually called "resultative", that describes "you keep the state where you have done". It implies the action itself is completed a while ago.

• 準備はできた (junbi wa dekita)
  • Q: lit. "Has the preparation finished?" ~ "Are you ready now?"
  • P: lit. "The preparation has finished." ~ "I'm ready now."

～た as perfect implies the action is freshly completed, or having done just before, if not now. As a question, when the speaker doesn't know about the progress, it has little meaningful difference with that using ～ている, though.

Answer 2

Most importantly:

1) "Junbi" (じゅんび）（準備) is better translated as "preparation".

2) "Ii" is in this case (as "ii" often is) used in a different way (close to kekkou, if you know that expression, in this case meaning "not needed").

All 3 seem like sentences that are expressed verbally, and, it is unclear if they are questions or statements/orders as you can't hear the intonations.

Regardless which one (question/statement), the latter 2 are more or less interchangeable, although the 2nd one may sound a bit awkward when used in the sence "I'm done with my preparations".

The first one, if not "having a ?" most often would mean "No need (for you) to prepare". It could also (without "?") be a response to someone asking "Junbi wa dekita?", in which case the meaning would be [possibly sounding a bit rude] "I ain't gonna do any preparations". As a question "Junbi wa ii?" would typically mean "So, I don't need to prepare?", but it could vary depending on the circumstance.