Depending on what kind of birds you are after you may have missed out. Wood ducks and teals are pretty much all gone by now but the mallards, divers and Canada's are starting to get on the move. The migration this year seems to be a little later due to all the warmer weather we've been having, although I'm in London so I can't speak specifically for the Barrie region. Most people prefer hunting in the morning as then it when the birds fly out to the fields to eat. An additional reason to hunt the morning is to prevent scaring the birds off by shooting the roost, which is the location (typically a pond or flooded area, they like to sleep near/on the water) that the birds go to sleep for the night. When the roost is hunted the birds will feel pressured and will leave the area. However, there is nothing illegal about hunting the roost, it is just kind of shooting yourself in the foot and is also detrimental to other waterfowlers in the area that hunt the same birds. However, there is still a wide variety of hunting that you can do during the evening, such as pass shooting the birds as they are flying towards their roosting area. This allows you to hunt the birds but still lets them feel safe in their roost. Obviously you will need to do some scouting to find out which fields or ponds the birds are feeding in and which routes they take to get places so you might not have a ton of luck this season unless you have already done your scouting. That being said with the colder weather coming you can expect the birds to be pushed down by in and they will come in fairly large numbers. You will also need to talk to landowners and get permission to hunt property as Crown Land is hard to find in Southern Ontario, there is also a number of Conservation Authorities that allow public hunting.
Southwest and Central Ontario