Babysitter needed

We live in Basel and are looking for a babysitter for our two children. We are looking for childcare from time. I specifically have a conference coming up in September where I will need someone to take the children to school, and then pick them up in the afternoon and stay with them until I return in the evening. I would ideally like the children to meet this person a few times before (for a few hours at a time) and then we would also like to retain the same person for future occasional needs.