Is it necessary to send my child to pre-school at 2-3yo? If not is there any disadvantages? Like hard to catch up the syllabus compare to others. Thinking to send her directly to K1.

I plan to start my kids at 4 too. It is a very personal choice and there are pros and cons of staying home vs sending your child to school early. To me I personally believe our children should enjoy as much as they can. I still send my boys for some enrichment classes and let them attend playgroups so I'm not too worried about socialisation. In any case, all kids learn at their own pace so I try not to stress too much over it :)