Beginning
In The Beginning, First Of All, To Begin With
expression
This is a time based word (because of the に). What is the first point of time when you are beginning something? That is the beginning.
This word uses the kun'yomi, which you didn't learn with the kanji, so here's a mnemonic to help you out. What are you beginning? You are beginning Haj (はじ). (Haj is the fifth pillar of Islam, and is a pilgrimage to Mecca during the month of Dhu al-Hijja).
まず初めに牛肉をスライスして、それからフライパンでいためてください。
To begin with, please first slice the beef and then pan fry it.
初めに言わせてもらいますが、アドリブえんそうはしないでください。
First of all, please don't improvise.
トーフグよ安らかに眠ってくれ。今月初めに、僕の一番好きな日本語学習サイトが倒産しちゃったんだ。
R.I.P. Tofugu. At the beginning of this month my favorite Japanese learning site went bankrupt.