Babysitter Needed for my Children - Full-time / Part-time

My husband and I live in Oxford with our 3. 5-year-old and 1. 5-year-old daughters (along with a Bernese Mountain dog who is a gentle giant). We're looking for someone to be with the kids on Mondays and Wednesdays from 9 until 6. Our 3. 5-year-old attends preschool for half days, so the first part of the day will be with just our 1. 5-year-old and then our 3-year-old will need to be picked up from school around 12. We're looking for someone who can take initiative, plan activities from time-to-time and be active and engaging with our girls. We'd love to find someone who fits in well and can grow with our family long term.