At first glance, this phrase may seem like the only option for indicating a first impression. However, there are several synonyms for this phrase that can add variation and interest to your writing. "Initially" suggests the very beginning of one's perception, while "primarily" conveys an emphasis on a particular aspect. "In the beginning" highlights the start of a process or experience, while "to begin with" indicates a starting point or introduction. Additionally, "at the outset" emphasizes the beginning of a journey or project, while "at the start" simply indicates the initial stage. By using these synonyms, you can convey a more specific and nuanced interpretation of a first impression.