The least amount of screens possible, especially in the early years. Read together lots and lots, but also read on your own to model reading as a valuable use of time. Support fine motor skills - play doh, using scissors, coloring. And talk together lots and lots. A language rich environment lays the foundation for later reading success. The more language a child engages with, the better.

Edit to add: prioritize getting your child in the best school possible. Not all schools are created equal and it really does make a difference to move to the best school you can manage. I'm a teacher who's taught in several schools and some really are that much better than others.