It depends a lot on the toxin. Some can be slow to present problems, and some fast. Some are readily dealt with and others are not. Some are produced as a byproduct of our own bodies, and others we ingest or are otherwise exposed to . And what is toxic can also be beneficial. For example water and oxygen are both essential for life, but they can also be toxic to the body. So it is not an easy thing to answer.
Our bodies also have various means by which to detox. The liver plays a primary role in detoxification as does the excretory system. The flora help to break down some toxic substances. Certain foods can help bind heavy metals, can help build the flora, and can help with the elimination of toxins. Breathing helps increase oxygen levels that can help oxidize certain toxins.
So the best thing you can do is to eat well, avoid stimulants, keep your stress down, avoid any pharmaceuticals that are not absolutely necessary, and cleanse your liver with bitters at least once in while if not regularly. Deep breathing exercises also help, and don't forget plenty of mineralized water.