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 think it's really up to individual on the pre school education. But of course if the caregiver who look after your girl could also teach her than it would be so much better. The reason for sending them to school perhaps is also to teach them to socialise too. Knowing how to communicate with friends and teachers. Also to build up their independent skills when they go to pre schools as caregivers are not around and they would need to try to do things by their own without help. These are all very important skills which is need when they promote to primary school.