All set means is everything prepared. If not, is it almost done.
The big day means the day you have been preparing for, usually a special or significantday.
You can also say "Are you ready for the big night" - means the same just a different time.
"All set"とは準備完了という意味です。そうでない場合はもうすぐ準備が完了するという意味です。
”The big day"とはあなたが準備をして来た日を意味します。それは通常特別または重要な日のことです。
"Are you ready for the big night"
(大切な夜のための準備はできましたか？)と言うこともできます。
これは時間帯が違いますが同じ意味です。
In England we commonly refer to a wedding as "the big day" before it has happened and a common question for a family planning a wedding is "are you ready for the big day?"
A more formal way to ask is "how are the preparations going for the wedding?"
イングランドでは、結婚式の予定日のことをよく「the big day」と言います。「Are you ready for the big day?」は、結婚式を控えた家族がよく聞かれる質問です。
よりフォーマルに尋ねるなら：
"How are the preparations going for the wedding?"
(結婚式の準備は順調ですか)
Since the wedding day is near, have you bought the wedding dress yet?
The noun 'preparation' is derived from the verb to 'prepare'. It is the act of preparing, that is, to make ready for something to be used or to be considered. Before the wedding, there are many things that must be done in preparation. For example, a wedding dress must be bought or hired for the bride. The bridegroom must also get a wedding suit tailored for him. A suitable venue must also be found. In view of the foregoing, you might want to find out from the bride or bridegroom just how far they have gone with preparing for the wedding.
You may ask:
How is the wedding preparation going?
or
Since the wedding day is near, have you bought the wedding dress yet?
「preparation」は「prepare（動詞）」の名詞形です。「準備（使ったり、検討するために用意すること）」という意味です。結婚式の準備では、やらないといけないことがたくさんあります。
ウエディングドレスを買ったり（借りたり）、新郎はスーツを仕立てます。式場も探さなくてはなりません。こうした点について、新郎や新婦に、準備が順調か尋ねるといいでしょう。
以下のように言えます：
How is the wedding preparation going?
（結婚式の準備は順調ですか？）
Since the wedding day is near, have you bought the wedding dress yet?
（結婚式が近いですが、ウェディングドレスはもう買いましたか？）
"The big day" usually is being referred to as a wedding day which is often a big event for someone's life.
"How is everything looking for the big day?"
"Will all of the preparations be ready in time?"
These two phrases and questions are great ways to ask someone if the preparations for their wedding will be in place. I hope that these two questions give you some more alternatives to asking about the big day.
"The big day"というフレーズは、通常人生の中でも大きなできごとである結婚式の事を意味します。
"How is everything looking for the big day?"
（結婚式の準備はどう？）
"Will all of the preparations be ready in time?"（準備は間に合いそう？）
この二つの文は、結婚式に向けての準備の進み具合を聞くものです。違う言い回しの物を２つ書きましたが、役に立つと嬉しいです。
An open question about the wedding plans would be:
"How are the wedding plans going?" Such a question leaves the person you asked total freedom to tell you whatever they please about the plans - good or bad.
Another way of putting this question is to ask:
"Is everything in place for the wedding?" This is asking if all the arrangements for the big day have been set up or are already in hand.
If for some reason it appears the organisers are under some stress or something is not quite right, you may have reason to ask:
"Have you had any hiccups with the wedding plans?"
To have a hiccup = to have a small problem with something:
For example, if you played a piece of music in a piano lesson that mostly went well, but had a few problematic spots, your piano teacher might say "Well, there were a couple of hiccups here and there, but it was mostly good."
結婚の計画について自由に答えてもらうための質問は、
"How are the wedding plans going?"（結婚の計画はどう？）です。
このような質問は、いいことであれ、悪いことであれ、相手が自由にその計画について話してくれます。
別の尋ね方は以下の通りです。
"Is everything in place for the wedding?"
（結婚に向けて、準備は全部できた？）
こちらの文はは、その大切な日に向けたアレンジが既に完了したかどうかを尋ねています。
もし何かの理由で主催者がストレスを抱えていたり、何かがうまくいっていなさそうだったら、以下のように尋ねるといいでしょう。
"Have you had any hiccups with the wedding plans?"
（結婚の計画で何か問題あった？）
To have a hiccup = 小さな問題があるということです。
例えば、ピアノで曲を弾いていて、ほとんどうまくいったけど、少し問題があった場合は、ピアノの先生は"Well, there were a couple of hiccups here and there, but it was mostly good."（まぁ、あちらこちらに小さな問題があったけど、ほぼ良かったよ。）と言うかもしれません。
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