から here takes a predicate and changes it so that it will mean a series of events, with one of its arguments ranging over an ordered set of things.
'I will kill you.'
'For x = x_1, x_2, ..., x_n, I will kill x in this order, where x_1 is you'
The difference between using
まず is that
まず takes a focus (which is the variable part of the implied events to follow) that is not necessarily the noun phrase adjacent to it. It can be the
を-phrase, the verb, the whole predicate, the
が-phrase, or whatever:
まず 君 を殴る [Focus: 君]
'First, I will hit you, then I will hit your brother, ...'
まず君を 殴る [Focus: 殴る]
'First, I will hit you, then I will kick you, ...'
まず 君を殴る [Focus: 君を殴る]
'First, I will hit you, then I will go for shopping, ...'
'First, I will hit you, then my friend will hit you, ...'
Depending on the focus,
まず-construction has several interpretation, and is ambiguous. One of the interpretations will be the same one using
から, so using both will not cause conflict.
A restriction on this usage of
から is that the predicate has to be telic (has an end point) in the relevant usage. With predicates that are telic, the construction is grammatical:
When the predicate is atelic, you cannot use this construction. The following are all ungrammatical:
Furthermore, it might be the case that for some speakers, the predicate also has to have duration. In the grammatical examples above, the predicates had duration, but the following predicates do not have duration, and it seems they are not completely natural:
They become more natural when duration is added to the predicates: