If you can afford to let go of your job, let go of it or inform your client that you'd like to take a sabbatical. If not, try to minimize your workload so you can focus on your studies. Instead of working 5 days a week, you can can work 1 to 2 days a week ra man. I think that beyond time management, it's also a matter of priorities. You can't serve 2 masters equally at the same time. Take mokiloo's advice.