同意你的看法。这里对 it 的分析确实欠妥。

这里的 when从句是状语从句没错，但 it 不应该分析为指代when从句，其实它是用于表示“时间”的非指代性用法（类似于 It is five o'clock 中的 it 的用法）。我们可以反过来想一下：如果把 it 理解成指代 when 从句，那 it 就成了形式主语，后面的 when 从句就是句子真正的主语（即主语从句），这与前面说的它是状语从句就是矛盾的。

首先，赞同蒋老师的分析。

但是，如果换个思路，推断一下薄冰老师的解释，是否可行呢？

按照薄冰老师的解释，他把it分析为形式主语，而真正主语是when we arrived at the village，如果这样，按照句意理解，在意义上相当于When we arrived at the village was rather early.把when理解为融合关系副词（也有称其为缩合连接副词），进一步转换为The time when we arrived at the village was rather early.但是，名词性关系分句（也有称其为名词性定语从句）是否可以作为外置主语的问题是有争议的。

1. Swan的Practical English Usage未谈及名词性关系分句是否可以作为外置主语的问题。但是，对于名词词组是否可以作为外置主语问题有这样的说明：

it一般不用作名词短语的先行主语。

The new concert hall is wonderful.

不能说：It's wonderful the new concert hall.

但是，在非正式文体里，it可以充当“名词+关系从句”的先行主语。

It's wonderful the enthusiasm that the children show.

It's amazing the way (that) they work together.

It's strange the way you know what I'm thinking.

2. Huddleston认为，名词词组外置时有一定的限制条件，而且使用范围是有限的。他还认为名词性关系分句不可以作外置主语。他这样解释：

(b) Extraposition of NPs

NPs generally cannot be extraposed, but there is a very limited range of types that can:

[13] i It’s extraordinary the amount of beer he puts away.

ii It impressed me the way she disarmed him.

iii It’s incredible the things they get up to.

The NPs concerned all have the form ‘the ... N + relative clause’. They are a special case of what we have called ‘concealed questions’ (see Ch. 11, §5.3): they are more or less equivalent to the interrogative clauses how much beer he puts away, how she disarmed him, what they get up to. At the same time, the matrix VP gives an exclamatory meaning: [i] conveys that he puts away an extraordinarily large amount of beer, and so on. Extraposition is optional: we can also have the basic versions The amount of beer he puts away is extraordinary, and so on.

(c) No extraposition

[6] a. What she suggests is unreasonable.

b. *It is unreasonable what she suggests.

Like ordinary NPs, fused relatives do not occur in the extraposition construction. Here too they differ from clauses: compare That we should have to do it ourselves is unreasonable and It is unreasonable that we should have to do it ourselves.

3. 但是，Bas Aarts认为what引导的名词性关系分句是可以作为外置主语的。在口语体里是非常常见的。

他这样解释：

Many constructions begin life confined to spoken language but make their way into writing,particularly texts that are not subject to the scrutiny of teachers and publishers' editors.As an example,H&P say that the example it is unreasonable what she suggests is incorrect,but the authors have noted the same construction,as in lt's unfair what they're doing to the union,in conversation,radio discussions,and examination scripts. Copy-editors would exclude it,but in speech it is very common.Because spoken language is not "self-conscious" or "self-monitored",it enables the potential for innovation to flourish,making it an ideal place to look at where language change is going.

至于when引导的名词性关系分句是否可以作为外置主语，则需要进一步证实或证伪。开头部分纯属推测。仅供参考。

网友提供句子有以下2种分析

【观点(1)】It【主语】// was系动词】//rather early【表语】when we arrived at the village【时间状语从句】 

备注：it指代时间。rather early可以换成 six o'clock ，when引导时间状语从句，描述从句动作发生时，it时间是什么时候,即it所指的时间是when从句动作发生时(钟表/当天)所指时间。

【观点(2)】按照强调句型理解It is/was+强调内容+that/when结构，强调内容为时间状语“rather early”

It was rather early when we arrived at the village 【强调句型】 

去掉以上It was when就是下面句子

we arrived at the villagerather early.我们很早就到了达乡村/村庄。