Fly day before. My partner and I went to bermuda last month on celebrity and booked our flight to ewr the day of thinking "it's June, no snow, what else could go wrong?" Well Porter decided to have a network outage that grounded their entire fleet. After twenty minutes of waiting in the lounge at YTZ, we decided that we didn't want to risk missing the cruise so we got two tickets on AC flight to LGA.
Thankfully the fare wasn't too disgusting (~$400 each), though I think we were fleeced slightly on the taxi ride from LGA to port liberty.
Even though it all worked out, I personally didn't feel relaxed till the following day.
The absolutely worst part was the taxi ride from YTZ to YYZ. We got the one Toronto cab driver who believed that the posted speed limits were gospel and that he wouldn't dare coming within 10 km/h of it, for fear of some form of Devine retribution.
In short, my partner and I will always fly the day before from now on, as we were quite fortunate that we had the means to afford the last minute fare, and that we live in a hub like Toronto where there were other direct flight options.
And as aside, PD refunded the fare for the missed flight and offered a $50 credit. Not enough for me to fly them again, unfortunately.