I don't think the issue is when your child does the homework, but whether or how the homework impacts family life. In reality, people function in different ways. Some are planners. Some do things the last minute. Despite those different styles, people still live good and productive lives. As long as your child is managing his work in a reasonably independent way, you're okay and you're better off supporting him doing it his way than adopting yours or some other seemingly "right" way.
You know you have homework problems when things seem grossly out of sync. Family life fails to match what you think it should be, and you find yourself acting in ways you would rather not. That's what happened in my family. For my oldest two kids, things went well. Once was more industrious than the other. One was more planful than the other. Both graduated from college and are successful in their careers. My youngest child, in contrast, had persistent homework problems. For him, I made the mistake of thinking that homework "had" to get done and that it was my job to get on his case. In retrospect, I wish I had insisted on homework relief. He would have gotten far more done if he had been given clear limits on the amount of time he had to spend on his assignments. I think one key factor that gets overlooked with homework is that parents are the rightful heads of their homes, and should make decisions that may overrule the teachers, when homework causes problems. I discuss this further on my website, www.thehomeworktrap.com.
Dr. Kenneth Goldberg, is the author of The Homework Trap: How to Save the Sanity of Parents, Teachers, and Students, published by Wyndmoor Press.
I recommend giving copies of the book to the teachers at your child's school. Discount purchases are available through Wyndmoor Press. Single copies can be purchased at Amazon.