To make school entry a positive experience for both you and your child, a number of suggested pre-school activities could be considered.

Talk about school in general and describe what will take place in a kindergarten class. The songs, stories, the art and play activities are a few that spark interest.
Explain that a French Immersion Kindergarten class is the same as in the regular program except that the teacher will be speaking French and that soon they will be able to understand all that she is saying.
Expose your child to French television programs, web-sites and, if possible, borrow French music from the municipal library. This will be helpful to introduce the child to words and sounds of the new language.
Use a few basic expressions in French such as Bonjour and Comment ça va? With the help of a book, try saying the colours or a few numbers together in French. Make it fun and show that you are interested in learning some new French words too.
Express how pleased you are that they will soon be going to school. Explain how proud you are that they will be learning French and how enjoyable it will be.