次第（しだい） is a
noun that is often translated in different ways, depending on what type of word it follows. In this lesson, we will look at the meaning associated with the
conjunctive form of standard verbs, and the stem of
する verbs. Although it is a noun,
次第（しだい） may also be classified simply as a
suffix in many cases.
Basically,
次第（しだい） means 'next in sequence after (A)', and is often translated to 'as soon as (A)'.
用意（ようい）が出来（でき）次第（しだい）、僕（ぼく）に声（こえ）をかけてください。
As soon as you get ready, please let me know.
ミュージカルが終（お）わり次第（しだい）、連絡（れんらく）をください。
Please call me as soon as the musical ends.
待（ま）ち合（あ）わせ場所（ばしょ）に到着（とうちゃく）し次第（しだい）、私（わたし）に連絡（れんらく）してください。
Please give me a call as soon as you arrive at the meet up spot.
One of the most important things to keep in mind with
次第（しだい）, is that the literal meaning in almost every situation is 'determining sequence'. This is unlike any standard phrase in English, but simply expresses that (A) is what will govern (B). Let's look at how this translates with different word types.
Verb
次第（しだい） - Verb determines the sequence of (B). Since a verb is not capable of making a choice, (A) simply 'happening' will result in (B).
Living noun
次第（しだい） - Noun determines the sequence of (B). Since living things can make choices, (B) will depend on (A).
Inanimate/abstract noun
次第（しだい） - Noun determines the sequence of (B). Since inanimate/abstract things cannot make choices, (A) will determine (B)'s course of action. (B) will usually involve some kind of decision.