She's already counting down to the big day.

她已经在对这一重大日子倒计时了。

《牛津词典》

The big day finally arrived.

这一重大日子终于到来了。

youdao

The fairest way to determine who gets the chance to wed on Sunday and ensure everyone can properly plan for their own big day is through a lottery system.

要决定谁有机会在周日结婚，并确保每个人都能合理规划自己的大日子，最公平的方法就是通过公平的抽签系统。

youdao

The students, including this fourth-grader, were excited for the big day.

VOA: special.2011.07.11

This is a big day in your life.

今天在你们人生中将非常重要

耶鲁公开课 - 基础物理课程节选

You can take these big risks of time, and if at the end of the day there's nothing to detect, you still know how to build a detector.

如果最后你什么都没测到，你至少知道了,怎么造一个探测器,所以如果你们。

麻省理工公开课 - 化学原理课程节选

It appears she is not the only bride in fear for her big day.

BBC: Stamps of disapproval over postal strike

"There's a tendency before the big day to sort of party it up, " Good said.

CNN: Biggest danger for hunters? Heart attack, not stray bullet

Voters, observers, election committees, and, of course, the police, are ready for the big day.

FORBES: While Moscow Sleeps, the Far East has Begun to Vote.