Well, give me a few months and I will probably have very strong opinions.
My son started school at 4.5, april child, amongst the youngest in his class. He has taken to it like fish to water. He is in year 1 now. He goes to tennis and karate after school, and has violin tuition. He is bilingual English Norwegian, and also speaks some polish and enjoys french.
We are moving to my native Norway in March, where children start school at 6.
Nurseries are usually full time from the child is 1 years old (when mum returns to work from maternity leave) till 6, where they go up classes every year, and do different things. The do a little number and literacy work, but, as in Switzerland I take it, the focus is on social skills, independence, crafts, such as woodwork, knitting, pottery, and home economics, and the outdoors. A lot of time is spent outdoor, a little rain does not scare a norwegian child from playing outdoors, they just dress up differently. They go skiing, and treking, they go to beaches and look at rockpools, make fire, in fact they learn a lot about nature and the natural world. Sorry I am not good at speaking briefly.
Now, my son who is half way through year one here has to start school in Norway. Even if he has gone to school for 2 years, he would have to start together with his age group if he starts in august.
Luckily he will be able to join a "fast track" class that integrates with current norwegian year one (they dont have reception) for gifted children. (weird) But will join his NEW year one in august where the rest of the children for year one starts. I guess time will tell how this will go.