Preparation is half the battle
and most of the Success
Yes, in a real situation you may not have the time and opportunity to prepare your mind and body but in day-to-day life you do not want to create the damage that an unprepared real situation could cause. The pre-training warm-up is the number one way of improving your stretching, preempting damage and accidents and testing yourself how you feel and checking how your energy level is to match it with the intensity of your training.
There is more than 30 minutes of warm-up here so there is some choice for you but initially, especially if your are not used to a complete warm-up, do it all. You will need to know it all when you wish to be graded. No advancement is possible without passing the Shaolin Kung Fu Academy Warm-up completely; unless there are special physical or mental circumstances. For this you need to contact Sijo.
If you wish to improve your flexibility then you need to add stretching to the end of your routine. Before the event, the warm-up prepares the body and mind for training and loosens the tendons and muscles. This will improve you flexibility and agility but if you have areas that need special attention, say calves to achieve that good Horse Stance or you have back problems and need to loosen you Glutes, then the best time is to stretch after your workout. We also strongly recommend that you speak to a specialist if any problem areas arise in your flexibility or stretching.
If you encounter any persistent or repeating pain in your training; consult/seek the advice of a medical profession; Western, Eastern, Asian; no matter who as long as they are a professional with other clients!