Approximately 3 hours from arrival at MCO to walking into a park is our rule of thumb, but that is assuming that everything goes right.
However, there's a lot of "what ifs" to consider starting with the fact your ticker says you'll be arriving in January and flying in from Ontario. The weather anywhere in the Northeast could cause delays.
You should allow 60 - 90 minutes after getting off the plane if using DME, then there's check in at your resort and time to travel to Epcot (not a problem if you're staying at one of the Epcot resorts). If you're running a little late you could just leave your bags at bell services, skip check in (unless you're on a dining plan in which case you must check in to get your dining plan activated) and head straight to Epcot. You can take a taxi to the Beach Club if you're not at one of the Epcot resorts.
I don't know if Akershus takes walk ups, but I wouldn't count on it. Whenever we've walked by there always seems to be many people waiting to be seated and when we've dined there it has been full.
I would book a reservation for dinner or plan Akershus for another day to reduce starting the trip with that much stress. You could book a non-cc guaranteed restaurant instead.
Edited to add: Saw your other thread. Since you're on the DxDDP you'll have to check in at the CR to activate your dining plan. Also, from CR it would be much faster to take a taxi because otherwise you would have to take the monorail to the TTC, transfer to the Epcot monorail, then walk through FW to Akershus.
Also since you said only restaurants with a cc guarantee would work, I'm assuming you're thinking of character meals. Some places that children enjoy without a cc guarantee in Epcot include Biergarten (buffet with the Oom Pah band and dancing), Chefs de France (Remy visits the tables with his last round starting at 2:50) and Teppan Edo (hibachi dining).
