The time of day a chemotherapeutic drug is given has an impact on the effectiveness of the drug, it's toxicity, and how much damage is caused to the immune system and other cells in the body. Delivery at optimal times in the day increases the patient's quality of life by decreasing the toxicity's they experience, and also allows physicians to increase the average dose that can be given.

Most hospitals are not set up to see patients at multiple times during the day. Some hospitals are beginning to take advantage of a variety of drug delivery devices, or drug infusion pumps, capable of administering chemotherapy, and other drugs, at different times and different rates throughout the day. These devices can be plugged into a subcutaneous catheter access port, commonly used for delivering chemotherapy, and can then administer chemotherapy at the optimal times.

Ask your doctor, or find a hospital capable or willing, to set you up with a programmable drug infusion pump for your chemotherapy.
Optimal times for delivery of many common chemotherapy's are known and published in: The Medical Textbook, Cancer: Principles & Practice of Oncology, DeVita, Hellman, Rosenberg, 4th edition.

Resource

Books:

Circadian Cancer Therapy, Hrushesky (ed.) CRC Press, 1994.

Cancer: Principles and Practice of Oncology, "The Application of Circadian Chronobiology to Cancer Treatment," editors DeVita, Hellman, Rosenburg, 1992.