I had a small claims occurred in April 03 - March 06, when should be the latest date for file a claims in Toronto Ontario Canada?

It's not exactly clear to us what type of damage or loss you suffered nor exactly when it happened. All of which are necessary to give you a specific answer to your question.

However, the general answer to your question is that for most damages suffered before January 1, 2004 the limitation period to file a lawsuit in Ontario is 6 years. For most damages that occurred after January 1, 2004 the limitation period is 2 years.