I've checked out the Chateau de la Moraine which is located on Yonge Street (N. of King Road). Basically, it is a daycare inside a French Public School "Academie de la Moraine" which is under the French School Board.
The Chateau de la Moraine is private and you have to pay. My sister talked to them and currently they charge about $500/month for 2 full days/week program. The Thornhill location will start in September.
The Academie de la Moraine (i.e. Public School) also has kindergarten (5 days/week for free) but kids enter this school need to know basic French. So they will do a test such as ask the kid to get a red pen from the table or sit down on the chair, something simple but important as there will be no English. I didn't dig for more information but my sister did. So what my sister told me is that this French public school also offers IB program from Grade 1-12 and according to the school, kids from this school will be able to manage both English and French and they can choose to go to a French program or English program when it is time for them to go to university. Sounds great, right? So they will take your kid if they pass the test even if you don't live in Richmond Hill.
Hope this information help.
Denise