Whether you are at the beginning of the year or are completely changing your routines because they simply aren't working (it happens to all of us), there are a lot of systems to learn. Start by prioritizing the systems you need in place immediately. Teach the most important ones the first day.
On the second day, review all of the systems learned on Day 1 and practice again. Add in anything you really need in place as long as your students are doing well with the first set of systems taught. Take a break from new learning on the third and fourth days. Just review. On the fifth day, you can add in a couple of new systems as long as your students are doing well with the others. Continue until everything is in place. Review regularly throughout the year.
If your students are not doing well with your systems: reteach and practice. Have the students that are sabotaging your systems be your models for the review. They will enjoy the attention, and you will prove to them and you that they know what to do (so you can remind them later). Don't forget to check that you are consistantly holding students accountable for their behaviors.
Limit how many new systems you teach in any given day and week. Break your full agenda of systems up over days and weeks at the beginning of the year. Add in new systems in once the current ones are firmly in place. Later in the year, systems can be reviewed as needed.
Explain the system: What is it, what it's for and why.
Model the system 3 times. First, model it the correct way. Then, model it incorrectly (exaggerated and silly). Lastly, model it correctly again. Have a volunteer help you model for the class, if needed.
Choose students to model the system. Have them model it three times: correctly, incorrectly and correctly again.
Have the whole class practice.
Debrief: What went well, and what didn't go well? What can they do differently next time to fix that?
Practice daily until your systems are habits for all of your students.
If your students are not doing well with your systems: Reteach and practice. Have the students that are sabotaging your systems be your models for the right, wrong, right. They will enjoy it the attention, and you will prove to them and you that they know what to do. Check to make sure you are consistantly holding students accountable for their behaviors. (This was my issue as a new teacher.)
That's it! Truly it's not hard to train students well. It just takes time and patience. I know it seems like you are wasting valuable instruction time doing this, but YOU'RE NOT! A well-run classroom makes teaching and learning a joy. You'll accomplish so much more if you don't have to constantly stop and correct students all day long.
Think of the time you are spending as an investment of time that will give you back hours in teaching time and productivity later in the year.
Remember: It's never too late to start having a great year.