Being a combination of に and the う-Verb 先立（さきだ）つ ‘to take the lead’, or ‘to precede’, this structure connects to both nouns and verbs in their dictionary forms, to indicate that (B) is a preliminary step required for (A). It may be interpreted as ‘before (A), (B)’, ‘prior to (A), (B)’, or ‘in preference over (A), (B)’.
Despite these several interpretations, the literal meaning of ‘standing before (A), (B)’ can be useful to remember, as it highlights the importance of (B) as a first step.
As 先立（さきだ）つ is a verb, it may be seen in its dictionary from when followed directly by another noun, or in its て-form when indicating the whole (B) phrase as preceding (A). Additionally, the formal-conjunctive form, 先立（さきだ）ち will often be used in preference of the て-form, as
に先立（さきだ）つ is a formal grammar structure.
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新（あたら）しい機械（きかい）を導入（どうにゅう）するに先立（さきだ）って、色々（いろいろ）な会社（かいしゃ）のサイトを見（み）てスペックを比較（ひかく）します。
Prior to installing a new machine, I will visit websites of various companies to compare the specs.
映画（えいが）の公開（こうかい）に先立（さきだ）ち、予告編（よこくへん）が公開（こうかい）された。
Prior to the release of the movie, the trailer was released.
引越（ひっこ）しに先立（さきだ）つ1日（にち）前（まえ）に洗濯機（せんたっき）や冷蔵庫（れいぞうこ）の水抜（みずぬ）きをしておかなければならない。
Washing machines and refrigerators must be drained one day prior to moving.
Fun-fact - 先立（さきだ）つ may often be seen paired with 物（もの）, and is a set expression in these cases that translates similarly to ‘means’ in English. This ‘means’ refers to the prerequisites required to enable something, and will usually appear in negative sentences, in order to show that one ‘does not have the means to do (A)’.
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海外（かいがい）へ移住（いじゅう）したいけど、先立（さきだ）つものがない。
I want to move abroad, but I don’t have the means to do it.
新（あたら）しい車（くるま）を買（か）いたいけど先立（さきだ）つものがない。
I want a new car, but I don't have the means to buy one.