I am going to respond first as an Instructional Designer in Education, then as a mom.
Start with what you want life to look like for him in a classroom, say, when he is in 6th grade. Now, lets look at a lot, though not all, boys in 6th grade. Bored, feeling like poor learners, burnt out..not enthused..a sprinkling of pleasers and a few self directed true thinkers...the quickest route to putting your son into the majority is forcing academia on hi too soon..a rigid routine...and robbing him of his natural, biological need for the following
MOVEMENT for the BRAIN and motor system
GROSS motor, large motor, leaving fine motor for later (no pencils !!) big fat strokes, drawing, then small art projects...do not let anyone force the abcs on a boy too soon..it is all ego ego ego, who can teach it, who can learn it and who can stick it on their bumper sticker..it has nothing to do with real skills
Make sure he has outside, problem solving..social, music, science (water tables, with tools to measure...building, bulding...moving...
Yes, to bedtimes, routines, nutrition, rituals..but creating more robots, forcing all of that that is developmentally for 6-7 year olds by all experts...is a crime in education. I see more k boys stresses...crying...mothers having to be in the classroom because the k teacher needs to move on...and then retention..or special education..because they were put into programs before they were ready. The greatest gift you can give a boy and even a girl, is play during their scientifically agreed upon play based years.
You will then have ample time to give them strong academia but with a baseline for problem solving because play is problem solving. Look at the stats. Many teens, Kids cannot solve problems any more..they can only fill in the blank..scantrons. We need scientists (to look at problems and think, writers to convey passionate opinions not correct answers on the SAT, Drs (who can work with patients and truly solve medical mysteries not just pass out pills, ) teachers who can meet the learning styles of many learners, bankers who can say enough when they see an economic avalanche, ....thinkers
Ok, as a mom to a boy and a girl...I encourage you to truly enjoy the next couple of years..you will be in school with them before you know it..and as you know, the system will be there waiting...rules, homework, assessing.. do not let any fear of not being ready take this away from your precious little ones tiny years.
I say good sleep, really good food, outside play..singing, an instrument, cooking, gardening, at home...limited tv :)..
A preschool that is developmental..not a daycare unless you need that..
stable teaching staff
animals at school (ducks, hamsters, bunnies, etc)
garden
a lot of free open ended art
Dress up
Group time for practice but not too long or boring (there are some boring teachers sadly)
time to work with other kids
time to work alone
variety
ask when they prep...definitely not during the school day but before hand..so that they are ready when kids walk in..
ok, of course, clean potty etc
be careful of overly academic schools..
look for a school where parents seem connected..
best of luck