Depends if you want to be "at the front" of the crowd or just "in the crowd" for rope drop.
Personally we like to be near the front so we plan on being at the TTC at least an hour before rope drop.
You will need 20-30 minutes to get from your vehicle to the TTC, across the lake on Monorail or Ferry and then through bag check and turnstiles. Add at least 15 minutes if you want to be near the front. If its a high crowd calendar day, you will want to add more time to this.
If you want to be at the front of the crowd and along the rope for rope drop, allow 60-90 minutes from when you park your vehicle (depending on expected crowd volume for the day)