I just read this question but was confused by a different aspect of the example sentence:
The question's answer is perfectly clear about the meaning, but I don't understand how the grammar of the part in bold works. When I see から I think of either 'from', 'because' or (if it's て-form) 'after'. None of these seem to work.
On it's own, the first clause (to me) reads
from the person who has finished drinking milk
but such a translation clearly doesn't fit with the rest of the sentence.
Is it a geneal rule that
verb-past + noun + から = as noun does verb
What about the tense/aspect of the verb? Some more examples would also be appreciated.