Background: Biomarker testing and identification of actionable genomic alterations (AGAs) in NSCLC patients have led to targeted therapy use and improved outcomes, particularly in advanced stages. We sought to evaluate the impact of different testing paradigms on TAT, particularly with respect to treatment decision and time to initiation of treatment, across three time periods. Methods: A retrospective review of stage III or IV non-squamous NSCLC patients at the Princess Margaret Cancer Centre (Toronto, Canada) was conducted. Both de novo advanced and patients with metastatic progressions are included. Cohort 1 (C1; 01/2015 – 01/2017) underwent reflex EGFR (EntroGen) and ALK (5A4 immunohistochemistry, IHC) single gene testing. Cohort 2 (C2; 02/2017 – 09/2020) underwent reflex next generation sequencing (NGS; Trusight Tumor 15), ALK and ROS1 testing. Cohort 3 (C3; 10/2020 – 01/2022) underwent reflex comprehensive NGS (161 genes, Oncomine OCA v3). Descriptive statistics are presented, including AGAs found and TAT from biopsy to result sign-out, and treatment related TAT. Results: Three cohorts of stage III and IV patients were identified, with C1 having proportionally more females (60%), never smokers (42%) with adenocarcinomas (98%). More patients with AGA were identified using NGS with larger panels (42%, 41%, 57%, respectively across C1 – C3). However, there is a longer median time from first oncology visit to treatment (14, 22, 27 days, respectively across C1-C3), and longer biopsy to treatment TAT trended towards more comprehensive testing (34, 38, 40 days, respectively across C1 - C3) in stage IV patients. Conclusions: As more comprehensive biomarker testing became available, more AGAs are identified with an increase in TAT from biopsy to sign-out and treatment start. Despite our institutional policy of reflex testing, future endeavours will be focus on ways to reduce TAT.