at first; in the beginning; originally
Used to describe an initial state or situation that later changes or contrasts with the present. Often followed by が or けど.
It was difficult at first, but I've gotten used to it now.
I didn't like him at first.
Common spelling for 'at first', emphasizing the initial stage or first time.
Also used, but 初めは is more common for 'at first'; 始めは can emphasize the start of an action or process.
From 初め (beginning) + topic particle は. The kanji 初め emphasizes the first time or initial stage, while 始め emphasizes the start of an action.