Flexible Hours - Nanny Needed

We have two children and are looking for extra help with our older child, who is 3 years old. We have a full time nanny who cares for both kids most days, but 3 days a week (Mon/Weds/Fri) we are looking for someone to do after school pickup for our older child at 11:30, take him to the park/various activities, and then take him home around 2/2:30. This will involve a 30 min walk from his school back to our house every day. We would love someone who is looking for part time hours - this will be 9-10 hours a week, but there are certain times where we may ask for additional help if our full time nanny is out or if we need a weeknight or weekend babysitter. Great for a grad student, etc!