You also need to be careful when it comes to teaching them reading/ alphabet and all the other stuff they learn in the first few years at school. Unless you teach them the same way they will do it at school it causes major issues. They will pick uplearning the aphabet and what it means very easily in teh first year at school anyways without us teachign tehm stuff they do not understand as they cannot read anyways.
My wife is a primary school teacher and the amount of kids that come in knowing their alphabet which is just the name for the letter rather than the sound (phonics) and then struggle to cope with the change of learning as they learn to read is amazing.
As well thinking the fact they can count to 100 means they know their numbers. First week back at school and at the meet the parents session 2 parents didn't understand the way their child was learning maths as it wasn't how they did it 30 years ago (this is year 3 she is teaching this year) and was offsetting everything the child was learning by doing it incorrectly.
Yet the school had a child who was 7 which had been abroad and had pretty much not started learning and caught up with 2 terms no problem.
The worst thing about parents is the competitiveness, they all want to be able to say my child crawled, walked, talked, read, added up and so on first as if it's a competition when it's not.
My eldest is nearly 6 and likes the Ipad or pc but is really limited to a few hours a week but instead him and his younger brother (aged 2) spend time out and about all year round going to farms, forests, walks, play areas and so on. They pick stuff up scarily quick and that includes the bad as well as the good. Trust your instincts and work with your child to help him/her learn but there is no race or my kid is the best