Move our 11 year old with his sister next June, or wait for a natural break?

Our son's IB school is about 50 minutes away by bus. He is in Grade 6. Our daughter turns 3 soon, and the school 15 minutes from us in LB Nagar is where we'd like her to start nursery. If he moved too, it would be one school, one set of timings, and our relatives nearby could help on bad days. He doesn't want to move. He's just been picked for a team, and the bus is where he talks to his best friend. I'm not inclined to override him for convenience alone, but two schools in two directions with a toddler isn't nothing either. So what I'm weighing now is timing more than yes or no: move him next June along with his sister, or leave him where he is until the end of Grade 8 and look again then. For those who waited for a natural break, did it make the move easier, or just postpone the same argument by two years?