Objective To explore the experiences of patients with advanced cancer regarding the timing of ACP. Methods This secondary analysis used data from the ACTION cluster-randomized clinical trial. 288 patients with advanced lung or colorectal cancer, WHO performance status 0–3, and with a minimum life expectancy of 3 months were included in this analysis. Results The mean time between patients’ cancer diagnosis and the first ACP conversation was 15.3 months (SD:19.4). The average duration from current cancer stage diagnosis to the first conversation was 8.9 months (SD:10.7). The timing of the conversation was perceived as “just right” by 217 (75.3%) of the patients. Patients who perceived the timing as too early were more recently diagnosed with cancer (9.1 months) or with their current cancer stage (5.7 months) than those who did not. Patients perceiving the timing as too late had shorter estimated survival times. Conclusion Patients with advanced cancer may benefit from earlier ACP than what is currently typically initiated in clinical practice. Practice Implications When initiating ACP conversations, several aspects should be considered, including patients’ gender, their socio-cultural environment, and their ability to perform daily activities, with or without limitations.