初めて日本に行った時、友達のお母さんが伝統的な和式朝食を作ってくれました。
The first time I went to Japan, my friend's mother made me a traditional Japanese breakfast.
If I wrote the opening of the sentence in the following manner, how would the meaning change?
最初に日本に行った時、
or
最初日本に行った時、
In this context, what is the difference between 初めて, 最初に and 最初?
Here is my reasoning.
最初 refers to the beginning of a time period or to the beginning of a series of events. (Cf. 日本に来たばかりのとき...)
As istrasci pointed out in his answer, the additional に strengthens the time reference. (Cf. 日曜日街に行く vs. 日曜日に街に行く.)
初めて is used, as far as I can tell exclusively, for things you do for the first time. (Cf. 初めて見た.)
The difference between
初めて日本に行ったとき、
最初日本に行ったとき、
is maybe best reflected in English as
When I went to Japan for the first time, [the first thing I did was to find a convenience store and eat natto and I loved it.]
When I first went to Japan, [I could hardly understand a word of what people said.]
In the first sentence, you talk about what Japan was like for you, as a first impression. In the second sentence, you simply talk about the time period, which coincides with your arrival in Japan.
最初に sounds wrong in your example. 最初日本に行った時 I believe is correct. The additional に is only needed if the "first" is like in a list of steps, or describing who/what is the first to do something.
- 最初彼に会ったときにはあまり強い印象を受けなかった。 → The first time I met him, he did not make much of an impression on me.
- まず最初 に ゆでて，次に味付けする。 → First boil it and then season it.
- 最初 に 到着したのはトムだった。 → Tom was the first to arrive ("The first to arrive was Tom").
Other than that point, assuming your second sentence is then just 最初日本に行った時, then they basically mean the same thing. The only thing I would say is that 最初 kind of implies many times, whereas 初めて doesn't necessarily imply any number of repetitions. At least that's the feeling I get from them, but that could just be me.
