In thinking about my past week teaching what is one thing I would do differently

Last week was our first week in class. All classes pretty good except for my 2nd period, which is filled with students that are use to my procedure. I had several problems form these students last year and this year it has gotten off to the same start. If i had to do over again i would have placed a seating chart to keep them from felling to comfortable and keep them form sitting by there friends.