There are many ways that I home school my 3 yr old in preschool activities. I am NOT concerned about "socialization" at this age because he gets so much exposure to outside family members at this time. I also DO NOT follow a strict schooling practice at this time because a 3 yr old doesn't have a vast attention span.
I currently follow the curriculum outlined in the letteroftheweek.com curriculum. We are currently learning the "letter of the week" geared for ages 2-5 and the "sound of the week" geared for ages 3-6. When I prepare for the "letter of the week" I create a small word document that contains the outline of activities, all the cards and images necessary to create a simple slotted poster to display the images and activities for the week. I print out the cards and such on card stock and then store each letter category along with various information about science and social studies in each letter assigned manila folder. The letter assigned manila folder is placed in a filling box. I also record sounds off of the internet with a free down-loadable sound recorder from goldwave.com. I then proceed to either youtube.com or an alternative source to find the "free" sounds (animal sounds, classical music songs or kids songs etc) from online. I organize these on our computer into various folders so that I can easily access the music or sound for the week. As far as books are concerned we find most of the books at our local library or else I try to find a similar book in nature that relates to the "letter of the week"
I also follow a similar routine for the "sound of the week" although I am still in the process of making this more organized and such.
The curriculum outlined from letteroftheweek.com is DEFINITELY enough to fill a full day of preschool activities. However, I only follow the curriculum loosely at this time.
Besides using letteroftheweek.com, I also follow a simple curriculum from homeschoolhowtos.com. This curriculum is REALLY simple and it is easy to use on days when you simply do not have a lot of energy to teach. The simple e-book can be downloaded that explains the curriculum in more detail. Basically, it entails sorting various projects in separate boxes and then one box is used per day in which the child can learn and explore. Examples of boxes may include box #1 containing puzzles, box #2 containing blocks, box #3 containing phonics books, box #4 containing playdough and supply and box #5 containing various coloring book pages. Around 30 boxes are created and stored away so that each day a new activity is completed for the day. Rotating the boxes each month leaves the preschooler excited to learn something new each day.
The curriculum given above is far than enough to fill a preschooler's day. But besides that I also include some DVD viewing and card viewing from YBCR (yourbabycanread.com) and allow my three year old some time to tinker on the starfall.com website. I try to limit the amount of media exposure in a day if I can help it.
That is what I have for now on how we do homeschool-preschool although our preschooler is learning much more by just observing momma and daddy in everyday life that it really can't be contained in a box of curriculum in any matter.