It depends on several factors. The things to think about are the number and health of the people using the toilet, the thoroughness of the composting process and to an extent, where you are located.
If the toilet is used primarily by your family, and you know they are in good health, then we suggest composting over at least a six month period that includes summer (for good ambient temperatures), and then leave the fresh compost to mature for a minimum of a further six months.
If the toilet is used by members of the public, and therefore, their general health is not known, then it's important to adopt a precautionary approach and ensure the primary composting process happens over a twelve month period, with a further six months maturation (ie emptied from the composting container).
For users located in tropical regions, where there is a higher risk of intestinal parasites, the UN recommend a two-year primary composting process to ensure all potential pathogens and parasites are destroyed in the composting process.
The composting process can be accelerated by ensuring a good balance of carbon and nitrogen (see our blog post), ensuring the container is neither too wet or dry, and potentially mixing/aerating the contents. However, if all of this sounds like to much work, don't worry, time will have the same effect - just leave nature to naturally do the composting for you.