Background/Objectives: Inborn errors of immunity (IEI) encompass various congenital disorders, resulting in immunity defects and recurrent infections. Home-based subcutaneous immunoglobulin replacement therapy (scIgRT) is the best treatment option for those with primary antibody deficiency (PAD). However, the lack of standardized procedures in patient training remains a challenge. Our study investigates nurses’ practice and perspectives, aiming to identify areas for improvement in at-home scIgRT practice. Methods: We prepared a structured survey regarding scIgRT, including needle choice experience and perception of adverse events, and distributed it among qualified nurses involved in patient training and scIgRT supervising. Results: We included 56 nurses with a median age of 50 years. Among them, 67.9% represented adult care providers, while 32.1% supervised IgRT in children. Most respondents (83.9%) used the classic or assisted with hyaluronidase scIgRT preparations. Single-channel needles were administered most commonly (85.7%). The needle length was mostly chosen solely by a nurse (57.1%) or in cooperation with the patient (23.2%). Next, 9 mm and 12 mm needles were used most often (92.9% and 78.6%, respectively). As expected, the 6 mm needle was more frequently applied for children compared to adults (n = 16, 88.9% vs. n = 11, 28.9%, p < 0.001), while 12 mm was primarily used in adults (n = 35, 92.1% vs. n = 9, 50.0%, p < 0.001). Visual skin fold assessment was the basis for the needle selection (58.9%), followed by the injection site rule (26.8%) or a choice between two available needle types for thinner or thicker patients (25.0%). Results of this survey indicate that, according to nurses’ opinions presented in this survey, the needle length could be associated with local scIgRT adverse events, such as side needle leakage or local burning. Yet, it was likely unrelated to general adverse signs, such as headaches or dizziness. Most respondents (66.1%) indicated that, even if local adverse events occur, patients are reluctant to change scIgRT preparation or needle length. Most participants (69.6%) reported that the optimal administration technique needs to be discussed with the patient before and during scIgRT. Conclusions: This study sheds light on scIgRT practice in Poland, emphasizing deficiency in needle selection technique. Future research should focus on standardized training and advanced needle selection procedures on patient outcomes, investigating the correlation between needle strategies and adverse events, as well as the effectiveness of scIgRT.