With 4 children, 3 grades and 1 pre-schooler, a schedule is a necessity. If I tried to fly by the seat of my pants, we would never get anything done.
First, let me say that I am definitely NOT an over-acheiver when it comes to homeschooling. We learn the basic subjects and everything else is life. I really believe that a good bit of school is living life and learning through daily activities (cooking, shopping, playing outside, etc...). I admire and am awe struck at some homeschool moms who teach 10 subjects a day and have their lesson plans written out for the year. That's not me.
I stick with the philosophy, the simpler, the better. This is the first year I will have a child tested at the end of the year, so I will get to see for sure how well I am doing. I'll let you know.
I also don't spend my entire day doing school. We do school in the afternoon because that is when my pre-schooler takes his nap. The mornings are spent getting ready for the day, eating breakfast and cleaning up around the house. After lunch, I put my little guy down for a nap and we start school around 1:30. On a good day, we are able to be completely finished by 3:30 or 4. Although, there have been "those days" where we are still trudging along at 5:30. Those are not fun days for anyone.
My best piece of advice for any new homeschooler is make a schedule that fits your family. Don't try to replicate anyone else's schedule because it probably won't work for you. Even though we do school in the afternoon, most moms I know do the majority of their school in the morning sometime. Some moms incorporate their 3 year olds into their lesson plans. Some moms do their schooling in the evenings. You just have to find the time and place that works for you. It took a lot of trial and error for me to figure out what works in our home. Don't be discouraged if things don't run smoothly at first.