When should I open an RESP?

RESPs do let you play catch up with government grants but You can only make up missed contributions one year at a time. e.g  on top of the $2,500 maximum you’re allowed to contribute to your RESP each year, you can make an additional payment of up to $2,500 to catch up on missed years of contribution. Whatever you do, don’t wait until your child is nine or older to start an RESP – since grants are only available until the year he or she is 17, there won’t be enough years left to make up the eight years’ worth of missed contributions.
Bottomline: the sooner the better