Go early and have the cash in your hand. Cash in hand can seal a deal, at your offered price, faster than anything else.
It's absolutely essential you know what stuff is worth, retail, retail used and private sale used. The three are different things. Retail used is based on the wholesale price vs the "I want to dump this POS that missed that duck last Fall." of private used.
Might be the wrong time of year for used shotguns though.
No gun shows in Ontario on Saturdays. Sundays from 0800 to 1200 only. Rochester, N.Y.(pop. of roughly 210,358) has a bigger and longer gun show than anywhere near TO(pop. of close to 3 million with another 6 million living nearby.).
Buying online or at price match from a big box store(who won't price match to a gun show or for used firearms.) means you get zero post sale support should you need it. You don't buying at a show either.