It is all right to practice yoga and weight training at the same time or at separate times. You could however, split the routine up over different times of the day or during different days, making sure that you do not over exercise, nor target the same muscle group over and over again.
Any workout should not exceed a period of approximately an hour, nor should it be undertaken as an obsession to fill up empty spaces in your day. As long as you build it up into your lifestyle, and workout for a reasonable amount of time (which you will come to decide), the effects of over exercising will not overcome you.
Do remember though, practicing yoga is a way of life and it has far more benefits when done so. Sow the right seeds to reap its benefits.