Objective: Timely dementia diagnosis is widely advocated, with potential benefits beyond traditional health outcomes including earlier access to services and supports, planning, and preserved agency. This study aimed to identify and prioritise the most important benefits and challenges of timely dementia diagnosis. Methods: A two-round modified e-Delphi process was conducted with 51 Australian stakeholders, including people living with dementia, informal carers, clinicians, advocates and researchers. In round 1, benefits were rated for importance, with qualitative comments captured. In round 2, benefits were prioritised using best-worst scaling, where participants selected most and least important items within a choice set. Challenges were examined in a parallel process using top five selection and ranking. Results: In round 1, ‘time to plan legal / financial matters’ was the most highly rated benefit (97%) and ‘access to services-specialist shortages’ was the most frequently picked challenge (59%). In round 2, benefits were ranked by mean individual-level frequency-adjusted best-worst scores. Preliminary findings suggest that the core health benefit ‘earlier access to right care and treatment’ ranked highest, but with high preference variability. Benefits representing access to independence/wellbeing supports, and improved care-navigation ranked next, followed by benefits related to time-sensitive planning. Carer-related benefits occupied an intermediate position, while intrinsic benefits or later-stage planning ranked lowest. The most frequently prioritised challenges concerned specialist service access constraints, limited dementia literacy, and complex referral and care navigation. Conclusion: Overall, prioritisation highlighted importance of benefits related to accessing independence/wellbeing supports and improved care navigation, which ranked among core health outcomes when trade-offs were required.