As you are traveling in F/J class, you would also have privileges at the KLM Crown Lounge in YYZ, which is shown as "situated opposite Gate C32 in Terminal 3 (take the lift to the AT floor). Opening hours: 08.30 AM - 11.00 PM"
According to maps, terminal 3 has two "fingers", one with the A gates, the other with the B and C gates. Delta's flights appear to go out of the A gates (today they used A6, A13 and A14). It isn't clear whether you can access the B and C gates from the A gate area, which is after the Canada/USA "pre-clearance" checkpoint.
Have a good trip!!!