We moved towns when I was in grade 2. Mum tells me how sad she felt for me with all the other kids knowing each other and me knowing no-one. But I don't remember it at all and certainly have no bad memories of it. It must have been far worse for mum! I believe children are very resilient and unless she had a specific problem with change just go to the local school now and make the decision re moving her when the time comes.
However be prepared that you also will have made friends and may not want to move!