The down payment varies from a minimum of 5% up to about 7.5% at the $1 million price limit. As you said, the incentive cannot be used to reduce that. Rather, the incentive, similar to a down payment, reduces the size of the insured mortgage, so it allows you to reduce the size of your insured mortgage without increasing your down payment, therefore lowering your borrowing costs.
On May 6th, 2019. See this statement in context.