Evening Help 2-3 days a week

We are looking for a nanny to help look after our 22 month old son and assist with general household duties, including helping preparing dinner, basic tidying up and cleaning, and helping with bathtime and bed time. I will be at home at the same time, but I might ask you to go to the supermarket and purchase groceries for me, take our son to the park (which is located 50m from where we live) etc.. Hours and days are flexible and we might require some ad hoc work on the weekends too.