“Everyday is one less day.” – Tom Ford
By starting with nouns you’ll be able to get a better overhead view of how this grammar point works.
NOUN + の + 時
NOUNだった + 時
It’s probably easier to see this in action. Let’s begin with just this portion of the sentence and not a whole phrase.
私は学生の時…
When I am a student…
私は学生だった時…
When I was a student…
The first one is present tense, the second is past tense. I highlighted the second one with some red to make that more apparent. The ellipses at the end (…) show that the sentence should continue! How fun for you! So, what kinds of things could you say in English, first of all, that start with these sentences (give it a try). Now, how would you do that in Japanese?
に or not to に?
The first thing we have to go over is the particle に and how it plays a role in this grammar point. Take a look at these two sentences:
a 私は学生だった時よく勉強しました。
When I was a student I studied a lot.
a 私は学生だった時によく勉強しました。
When I was a student I studied a lot.
The italics are there to show what part of the sentence gets emphasized. When there is no に the emphasis is on what you do or did (the studying). When there is a に, the emphasis goes on the “when” portion. Other than that, the meaning isn’t much different. It’s also a slight enough emphasis where if you do the wrong one it’ll be okay. I’m not saying it’s you shouldn’t care, but it’s not a huge deal.
Continuing The Sentence
Okay, time to take a step back. So with に or without に it doesn’t matter a huge amount. Let’s see what we can do to continue some sentences.
a 子供だった時にパワーレンジャーになりたかった。
When I was a child I wanted to become a power ranger.
a 大学生の時日本語を勉強したい。
When I’m in university I want to study Japanese.
a 小学生だった時ディズニーが大好きだった。
When I was an elementary school student I loved Disney.
See how the に doesn’t really add or take away too much? Just a little bit of emphasis difference.
Now that you’ve seen nouns, let’s move on to adjectives. They’re similar to nouns in some ways.