Since my students already know that this assessment will be individual, they come to class ready to work independently so I have the exam papers face down on their desks ready for them when they come in. They may begin working as soon as the bell rings, to provide equal time for all students regardless of what their previous class is. My video explains why having this assessment be student-created is important. I have included sample exam questions if you need to add some to what your students create or if you're really not comfortable using student-generated questions.
While my students are testing I take the opportunity to walk and observe which ones are still struggling with which skills and/or content pieces. Because of the assortment of problems in this assessment, students have the opportunity to build skills at making sense of and persevering to solve problems, reason abstractly and quantitatively, model with mathematics and use tools appropriately. For example, the real-world problems need all these skills as students move from sorting out the meaning of each problem to creating a model to solve the problem and then solving it. (MP1, MP2, MP4, MP5) By the time they turn in the tests at the end of class I can usually tell whether or not I'll need to do any reteaching or individual remediation.
I post the following questions on the board before the end of class and ask my students to answer them on the back of their test. Their responses give me feedback about this approach to creating meaningful assessments.