Background: Timely treatment for colorectal cancer (CRC) is a quality indicator in oncological care. However, patients with CRC might benefit more from preoperative optimization rather than rapid treatment initiation. The objectives of this study are (1) to determine the definition of the CRC treatment interval, (2) to study international recommendations regarding this interval and (3) to study whether length of the interval is associated with outcome. Methods: We performed a systematic search of the literature in June 2020 through MEDLINE, EMBASE and Cochrane databases, complemented with a web search and a survey among colorectal surgeons worldwide. Full-text papers including subjects with CRC and a description of the treatment interval were included. Results: Definition of the treatment interval varies widely in published studies, especially due to different starting points of the interval. Date of diagnosis is often used as start of the interval, determined with date of pathological confirmation. The end of the interval is rather consistently determined with date of initiation of any primary treatment. Recommendations on the timeline of the treatment interval range between and within countries from two weeks between decision to treat and surgery, to treatment within seven weeks after pathological diagnosis. Finally, there is no decisive evidence that a longer treatment interval is associated with worse outcome. Conclusions: The interval from diagnosis to treatment for CRC treatment could be used for prehabilitation to benefit patient recovery. It may be that this strategy is more beneficial than urgently proceeding with treatment.