If you incoporate Oly Lifts into your workout, I would recommend performing the exercise first after a complete warm-up. The reason behind this is that since Olympic Exercises are very complex and involves the wholebody it is important that you do these exercises first in your workout, especially if you are working with heavy loads.
It is not smart to go from say a squat to doing power cleans. Reason being, your legs will be fatigued and the technique of the power clean with be off cause there to be more room for injury.
If you want to incorporate oly lifts but choose not to perform them at the beginning. I would highly recommend you focus on performing with a lighter weight. There is no reason to try and go ahead and break records while your body is already fatigued after part of your workout.
Personally when I do Oly Lifts, I start to feel a sense of excitement and it activates the rest of my body for the remainder of my workout. Since Oly lifts are highly neural, it really wakes up your body and gets your mind and body amped up which is why I would recommend performing these exercises first.