Not all courses go on sale at the same time and when they do, it could be for a number of reasons.
We have the following cases:
1. Last Minute seat sales
2. Early bird pricing
3. Special course pricing
Last minute seat sales will generally occur 1-3 weeks prior to the specific course date.
Early bird pricing is set differently for each vendor and is not easily explained. Some companies list early bird pricing and then immediately to Last Minute seat sales while others will advertise early bird seats starting and ending 6 months before a course date.
Special course pricing is completely unpredictable as they are courses with special circumstances. For example, if a course is new and the company would like to give a push to advertisement by offering all seats at a discount for the first few classes or there are a larger than normal amount of seating left available and a company wishes to sell them off immediately.