If you're competing in a weightlifting meet, you can either power or full clean the bar off the floor. Just depends on which lift is stronger for you. For the jerk part, if you're maxing, it would not be optimal to immediately transition into a push jerk. You can throw more weight overhead by resetting in the front rack and then either power or split jerking. If you're talking about within the context of a WOD, like, say, Grace, power clean to push jerk is actually the best way to perform the movement. It's not "wrong" in any context, just not optimal in some. Hope that helps.