〜たら for the perfect aspect / completed actions / resultative state


This is something I've noticed for a while but I want to be sure of it. I just
encountered the sentence “準備したらおいで。” in context I'm fairly sure this means
“Come when you're ready.” and I've encountered it many times. “準備する” however
does not mean “to be ready” but “to get ready”, “to be ready” would be
“準備している” or “準備ができている” if I not be mistaken. Thus, I would expect “準備してたらおいで”
instead. After all, the character is beckoned to come when being ready, not
when getting ready.

I've seen this multiple times “気づいたら” is of course a fixed idiom which I found
counter intuitive from when I first saw it, I had expected “気づいていたら” for that
meaning, the same with “帰ったら” clearly meaning “when I get home”. Again, I
would have expected “帰っていたら”. Indeed “〜ていたら” does not seem to occur at all
much and I don't think I've ever seen it.

So does “〜ていたら” simply not occur at all, and as such is the usage one would
expect it to have assumed by “〜たら” with the difference being contextual? Can
“帰ったら” also mean “when I go home” opposed to always “when I get home” with the
difference being from context or does it always mean “when I get home”? and is
this simply how “〜たら” works?




As a native Japanese speaker, I use たら without thinking how it works, but [たら
has multiple roles](https://japanese.stackexchange.com/a/1784/5010). According
to the link, when たら is followed by a clause showing intent, invitation,
request, etc., it usually refers to the time when the said action is complete.
For example, 食べたら教えて means "Tell me when you _finished_ eating". You must not
use the teiru-form in basic cases. 準備する is a verb that means "to prepare". I
think it's a plain action verb like 走る and 食べる. That's why you have to say
準備したらおいで in basic cases.

However, since たら has many roles, we say 準備してたら or 準備できてたら in certain
situations. Note that, just as 走っている or 食べている, 準備して(い)る can mean either "is
preparing" (progressive) or "has prepared = is ready" (perfective), depending
on the context.

  * 準備してたらおいで。  
= 準備できてたらおいで。  
If you're (already) ready (now), come (but if you're not ready yet, don't
come).

  * 旅行の準備してたら古いアルバムを見つけた。  
I was preparing for a trip and found an old album.

  * もっと準備してたら成功しただろう。  
If I had been better prepared, I would have succeeded.

