Ideally, a Maltipoo should be walked two times per day for a total of at least 40 minutes. A good goal to have is two walks of 20 minutes each. If needed, do a 30 minute walk and a 10 minute walk, or another combination that works best for you. Most dogs do best with a walk in the morning, and then another in the evening.
Keep in mind that a lively walk about 2 hours before bed can help a dog sleep; however, this is the cutoff line, exercise too close to bedtime can cause an increase in adrenaline that can make it difficult for a dog to settle down and relax.
Walks should be at a pace that is brisk for your puppy or dog. It is up to you to control the pace. If it were up to some pups, they'd be dawdling and stopping to sniff every other second. More details ahead on walking tips.
In addition to these 2 walks per day, most Maltipoo can benefit from a 20 minute outdoor play session, or an indoor one if there is inclement weather. This can take place at any time, and you'll find that your Maltipoo will let you know when this is needed. Typically, when a dog starts to get restless, there'll be excess barking, pacing, whining, or other such behavior. This is often a sign that there's a need to get out and release some energy, and have some mental and physical stimulation.
Added benefits of this sort of exercise session are that it's a great time to teach commands (come, fetch, give, etc.) and playing one-on-one with your dog helps strengthen owner-to-dog bonding.