I agree with just reading books as a good start. Make sure he/she has a good understanding of numbers and the alphabet.
I was the youngest in my family and when my siblings were at school, I remember asking my mother to teach me to read. We actually started with the Encyclopedia Britannica. She read to me and I learned simple words as she read. We also had a world atlas which intrigued me and I learned geography and map reading very early.
The only problem was that when it came time to learn reading in 1st grade with the Dick and Jane readers, I was so painfully bored with school that I almost completely lost interest in school.
So extreme boredom with school can be a problem. That can lead to class disruption.
My kids went to Catholic school for all but the first couple years when we didn't live near a good one. The local public school had a good reputation. When my son entered 1st grade he was in a big class and we got a call from the teacher that he was being disruptive in class. I met with the teacher and she acknowledged that the problem was boredom. There were 4 other boys in the class who were equally disruptive - also because of boredom. Since I worked nights, we came to a creative solution. Every day, I went to school and took the 5 disruptive/bored kids to the library to allow the teacher to focus on fundamentals with the rest of the class. The assignment I gave the boys was to pick a topic and research that topic, write a report and present it to the class. I forget what topics each picked but I remember one boy's topic was dinosaurs. It was valuable for the teacher to focus on the kids that needed to learn basics without disruption and for the advanced students to learn researching a topic of interest, writing, public speaking and independent thinking at a very young age.
My wife isn't well educated but I credit her with my children's quick start and excelling in school. She spent hours each day teaching numbers, the alphabet and nursery rhymes. As infants, they had foam numbers and letters that stuck to tile that we'd play learning games with while they were bathing in the tub. After alphabet recognition, they would start to make words on the wall. She would even teach them about all sorts of animals and the sounds they make.
For my preschoolers, I added learning numbers and alphabets in Spanish, French and German which they took to very well. By the time they reached 1st grade, they could recite the alphabet and count to 20 in all of those languages.
When it came time to learn about money, instead of just teaching denominations and simple ways of making change, for example making 75 cents change for a dollar doesn't have to be just three quarters but it could be a quarter, 4 dimes, a nickel and 5 pennies. I could see that spurring enlightenment and imagination in their eyes.
When they leaned graphing with the x, y axis, came home and were excited to tell me about it, I then introduced them to another axis - z, as an introduction to three dimensional measurement. Cartesian coordinates.
Here are some other places to look.
https://thislittlehomeofmine.com/homeschooling-kindergarten/
http://www.confessionsofahomeschooler.com/blog/2014/02/homeschooling-101-creating-lesson-plans.html
https://www.education.com/lesson-pl...jLvYDzCdTymKRiSFFG5r8c5szqSSmQeEaAu0jEALw_wcB
https://www.abcmouse.com/landing/se...DH-cqxhdnoMNXsZ_ZdpxneveJcPdo6UgaAkOPEALw_wcB
https://start.k12.com/schoolindividual.html?st=mo&product=mova&leadsource=sem&vendor=acronym&utm_source=Google+Adwords&utm_medium=cpc&utm_campaign=MO>SEM>Non+Brand>Google>MPS>Home>Phrase&utm_term=home schooling kindergarten&ad_group=MO>Home>Home+Elementary>Homeschool+Kindergarten>Phrase&lead_source_detail=Google+Adwords&keyword_match=p&adposition=1t3&ef_id=Cj0KCQjwo7foBRD8ARIsAHTy2wm2TW5xunnnJbEHYdA9aP9JCwHm-56yHnDdaJ-ADkjYXNSLtaqd6ScaAg2AEALw_wcB:G:s&s_kwcid=AL!2165!3!344631256461!p!!g!!home schooling kindergarten&gclid=Cj0KCQjwo7foBRD8ARIsAHTy2wm2TW5xunnnJbEHYdA9aP9JCwHm-56yHnDdaJ-ADkjYXNSLtaqd6ScaAg2AEALw_wcB