ワードアップ英会話 WORD UP ENGLISH CLASS | 日記 | Natural expressions: "in" for future times

I sometimes hear my students use expressions like "after two weeks" or "five days later" when they are talking about future plans or events. But usually it is more natural to use the word "in" when talking about how much time it will be until something happens.

So, for example:

"I'm going on vacation in two weeks." (not "after two weeks" or "two weeks later")

"The meeting is in three days." (not "after three days" or "three days later")