I am in NZ so it is a bit different here. Kids usually start school when they are 5. Some remain at kindergarten but they have to start proper school before 6.

Our kindergarten is next door to the school so there is interaction between the school and kindy. Sometimes the new entrants come back over for a visit and once a term the kids that are about to go to school go over for a visit and spend some time in the class room. We are also welcome to do school visits any time we want to as long as we stay with our child. I have personally taken my DS over for 7 or 8 visits. I then decided he wasn't ready enough for school so have elected to keep him in kindergarten until the start of next year when he will start with a bunch of kids from kindy that he knows (my DS has change/anxiety issues).

I have been very happy with the support of my kindergarten in transitioning DS towards school. The teachers take the time after school visits to gently ask him how things went and what he was feeling about it (which was helpful to me in the decision that he wasn't quite ready yet).