I started at a week per dr. for just a few minutes now at 8 weeks he does more but most of the time just falls asleep during tummy time haha

i think it depends on the baby cuz both of mine were advanced so my daughter started around a week old and she loved it it was her favorite part of the day and my son started tummy time at 3 days old he loves it too i just try to pay attention to how they act with it my babys are awake longer than most so they tend to play more

As soon as you can, few minutes at a time. You can start the day they come home, on your chest

I started at about two weeks for a few minutes & try to every day.