I think there is lots of things you can do to develop your child into an intelligent thinking bright person starting from early age. I am in favour of slow consistent approach. This way children get clever and bright without even realising it, and they learn effortlessly stuff that other children may not find so obvious or easy just because they didn't come across it in their childhood.
. I would say: talk to him a lot, using full sentences and interesting vocabulary, not just baby talking, with this consistent approach his verbal abilities will be well developed, he will naturally, unconsciously develop a sound language base. Sing to him and with him a lot of nursery rhymes, read a lot of books together. If you have any letter shapes, play around with them, buy alphabet puzzles or letter shapes that he needs to fit in the right place, etc. let him do lots of colouring and playing with play dough as it will develop his hand coordination and help in handwriting later, do lots of different puzzles of different sizes, children love puzzles and it helps develop their cognitive skills and problem solving. As for maths, count out lout to him a lot, for example when you are counting toys or building blocks, after a while he will surprise you by being able to count himself! It is never too early to start developing your child's intelligence. If you have ipad or android, there is plenty of free educational apps that he will enjoy and learn at the same time. When you are out and about, you can prepare a list of things you will see on the way, with a small picture and writing close to it, simple things such as tree, grass, etc, make him tick every thing on the list he will spot on the way, you can do the same while shopping. Once home you can read out loud words together.
Teach him the alphabet by singing a lot the alphabet song. You can do that while you are playing together, sometimes you can point to letters as you sing or hold his finger and guide him to point to the right letters once he knows his letters, you can make up your own song with your own melody to teach him the sounds of the letters, such as "a says a, b says b, etc till the end.
I did it all with my three kids and they all loved it and started school well ahead of their peers being able to read and write and count already. That will give him a head start.
There is so much you can do at home to help your child and support the school. This is just the beginning.