In the early stages of pertussis, timely initiation of effective antibacterial treatment (including prophylactic medication before symptom onset) can halt disease progression. In China, where measures such as maternal immunization are currently lacking, this remains a crucial approach to preventing severe illness and death from infant pertussis. However, a clear and unified time-based standard defining this "early stage" is lacking, and few studies focus on diagnostic strategies targeting early treatment. Based on the natural disease course of pertussis and limited clinical evidence, a time criterion of within 7 days from illness onset is proposed in this article for early diagnosis of pertussis. Strategies to promote early diagnosis are discussed: raising public awareness to encourage early medical consultation for infant pertussis; enhancing clinical recognition to facilitate early suspicion and testing; emphasizing the cough history of close contacts; identifying early clinical features such as the triad of afebrile status, rhinorrhea, and cough; noting significant increases in white blood cell count and/or lymphocyte proportion in routine blood tests; prioritizing etiological methods for diagnosis or exclusion; and urging health authorities to establish coordinated active surveillance and screening mechanisms between hospitals and disease control institutions. This article aims to support clinical research, standardize early diagnosis, antimicrobial treatment, and chemoprophylaxis of pertussis, and ultimately minimize severe cases and deaths in infants.