The dumbbells will fatigue your smaller muscles first before your larger muscles. Therefore, your larger muscles will not be fatigued when you reach the machines.
Here is a fitness tip! When stretching your muscles before or after your workout, hold each stretch position for at least 30 seconds. In the same way that it takes time to build muscles or lose weight, effective stretching does not happen instantly. Giving each pose at least a half a minute of stretching will ensure your muscles get thoroughly limber.