From someone who has been there: don't worry about misloads as much for now. When you're on your packet you need to be focused on pph and making your supervisors happy. Showing up to work on time every day is very important. The paper you initialed is simply acknowledging that you had misloads, this is different from being written up. From the point you initial that paper, they have 10 working days to write you up. After that, they can't do anything.
Once you get off your 30 days, join the union as soon as possible. Then, misloads and load quality should be your only concerns. Attendance should always be a concern. They can't write you up for speed, but they can get you for not following methods, attendance, and for misloads.
You can do it! I was in your shoes before and I did it. It's not easy but once you have a few months of experience, they will leave you alone. Dealing with this situation will make you a stronger person, and you will be more resilient when dealing with management in the future.
