I thought that I would share what I did to homeschool preschool Luke when he was 3-4 years old.
My goals were:
1) That he would read the Bible (a kids' Bible) through and learn about the characters
2) That he would learn his letters - what they were, how to write them, and what they sounded like
3) That he would learn his numbers 1-9 - what they were, how to write them, and how to count to each number
4) That he would learn his shapes - what they were, how to draw them, and what things were the shape
5) That he would learn his colors - what they were and what things were that color
I decided to do 26 weeks of school:
We read 2 Bible stories and did a coloring sheet and/or craft each week
We did one letter each week - traced and wrote them
We did one number each couple of weeks - traced and wrote them
We did one shape each few weeks
We did one color each few weeks
We did holidays, months, and seasons as they came
I got a ton of learning workbooks for letters, numbers, shapes, and colors and photocopied them (so I could reuse them or make multiple sheets if he wanted to do extra). I just grouped the worksheets by category and put them in the order we would do them. It was pretty organized but also pretty flexible. I also went through his Bible and printed coloring sheets and craft ideas from the Internet. We also talked about each month, holiday, and season and had coloring sheets and crafts for those as well.
It was a great way to start school as we didn't do that much and most of it was pretty simple. The goal wasn't perfection but getting a start for future learning. We also read, colored, did Play-Doh, did fun crafts, and did puzzles and games a lot as well.
I hope that has helped. I would love to hear how you homeschool your 3-4 year old.