I think the 5 minutes per month of age, twice a day is a good rule of thumb to start with. My toys since they reached adulthood need around 1-1.5 hours/2-3 miles of off leash walking to keep them fit and happy, plus games, brain work, etc. On days when there is a lot happening a shorter walk may be in order, but much less and they are bouncing off the walls. If I had a young spoo I would definitely be reckoning on several hours a day of walks, outdoor play and training games - poodles are easily bored, and bored dogs find ways to amuse themselves, or get stressed. At the same time it is important to be careful about the type of exercise - any amount of gentle puppy noodling is excellent; excessive jumping or stairs or mountaineering may put too much stress on forming joints.
To sit with a dog on a hillside on a glorious afternoon is to be back in Eden,
where doing nothing was not boring- it was peace.
~ Milan Kundera