Timeframe:
When you leave a training class, you must understand that your memory and your skills begin to deteriorate immediately. After the class, you no longer have the benefit of the instructor telling you how to perform the skills anymore. All of the training is done, and now the building of the skill begins.
Practice makes permanent:
To fully ingrain what we have learned in any training course, it is best to repeat those skills immediately. This will give you a better long term memory of the skills, as well as make them more intuitive should you need them. It also lets you work from your notes and remember the things that you needed work on to make it perfect. Remember, practice only reinforces what you are doing. It makes permanent practice of your actions, and if those actions are not correct, it will take more time to undo the bad habit. If you practice techniques, as taught, immediately after the course, you will have the details fresh in your mind. This will naturally create better practice habits.
Remember, a good training class is just a template for practice. Even the best teacher cannot make you proficient in their techniques in two days. It takes the work after the class to fully integrate the new techniques.