That was for the two of us but you would only need to trim a minute off. Note the 600W setting - our microwave is more efficient at settings lower than max.
If you eat porridge regularly it might save money to blend your own. Starting from a 50:50 ratio of rolled oats and jumbo oats, more rolled gives a smoother porridge, more jumbo gives texture. You can go fully to both ends of the scale - we have 100% Scottish Jumbo.
If you are buying larger bags, remember to store them in critter-proof boxes. Both mice and bugs love crushed grains as food!