Background: Overall survival for patients with pancreatic ductal adenocarcinoma (PDAC) and colorectal cancers (CRC) has increased significantly over the past decade; however, the optimal time-to-treatment initiation (TTI) and initial treatment modality (ITM) have not been defined. These variables have likely been affected by increased adoption and changes in types of neoadjuvant treatment strategies for these cancer types. Thus, we performed a retrospective observational study of TTI and ITM in patients with CRC and PDAC within the MHealth/Fairview medical system. Methods: We identified 424 patients with stage I-III RC and 316 patients with stage I-III PDAC within the MHealth/Fairview system (Minneapolis, MN) from 2011-2021 with North American Association of Central Cancer Registries data enriched by the electronic health record. Patients were stratified by TTI from diagnoses as: 0-7 days, 8-14 days, 15-28 days, 29-42 days, and over 43 days. ITM, defined as initial chemotherapy/chemoradiation, surgery, or radiation, was analyzed independently for patients with rectal cancer (N = 267) and PDAC. Effect of TTI and ITM on overall survival was calculated using a Cox proportional Hazard (CPH) model controlling for clinical stage. Results: TTI was significantly associated with survival in CRC, with patients treated in 8-14 days and 15-28 days showing increased survival over patients treated in over 43 days (HR 0.397, p = 0.007 and HR 0.276 p < 0.001, respectively). There was no significant hazard for TTI and survival in PDAC. We also found that neoadjuvant chemotherapy/chemoradiation had a lower hazard for death in rectal cancer relative to upfront surgery (HR 0.323, p = 0.002), when controlling for stage. Surgery was significantly more likely to be correlated with stage I or II disease than chemotherapy/chemoradiation (68.5% vs 24.7%, p < 0.0001 by Spearman method). There was no significant association between ITM and survival in patients with PDAC. Conclusions: Early treatment for CRC is associated with improved survival in this population, implying that treatment delays decrease the efficacy of curative-intent therapy. Evaluation of treatment modality in the rectal sub-group showed improved outcomes with neoadjuvant chemotherapy and chemoradiation, despite upfront surgery being associated with lower stage. The lack of association between TTI and survival in PDAC is likely related to the relatively poor outcomes observed with this disease and highlights the need for better screening and treatment for resectable disease. These results are notable because they suggest that a thorough workup and appropriate therapy may be more important than rapid treatment.