The optimal timing for vascular access (VA) creation before hemodialysis (HD) initiation and its impact on VA outcomes remain uncertain. This study examined the association between VA creation timing and access outcomes in HD patients. A retrospective cohort study using National Health Insurance Service data included patients who initiated HD between January 1, 2013, and December 31, 2021. Only those who underwent VA creation before HD initiation were included. Patients were categorized by VA creation timing: within 6 months (AV0), 6–9 months (AV6), and more than 9 months before HD initiation (AV9). Outcomes included catheter use at HD initiation and patency failure rates. Primary patency failure was defined as an event requiring percutaneous transluminal angioplasty, stent insertion, or thrombectomy. Secondary patency failure was defined as an event requiring new VA creation or catheter insertion. Multivariate Cox proportional hazards regression was performed to assess the association between VA timing and patency outcomes. A total of 48,110 patients (mean age: 64.1±13.3 years; male: 62.2%) were included, with 42,261 (87.8%) in the AV0, 2,302 (4.8%) in the AV6, and 3,547 (7.4%) in the AV9. The hazard ratio (HR) for catheter use at HD initiation was significantly higher in AV0 (HR 7.75, p<0.001) compared to AV6. Compared to AV6, AV0 had a 38% higher risk of primary patency failure (HR 1.38, 95% CI 1.31–1.46) and a 63% higher risk of secondary patency failure (HR 1.63, 95% CI 1.50–1.76). No significant difference was observed between AV6 and AV9. Patients who underwent VA creation within 6 months of HD initiation had higher catheter use and increased failure of primary and secondary patency. These findings suggest that optimal VA planning and timely creation may improve VA outcomes in HD patients.