I understand migrating to Aurora is simply a matter of creating read replica from MySQL source and then promoting when caught up and stopping writes on MySQL RDS previous master.
I use Route 53 DNS that has a CNAME record. My plan is to just change the DNS to Aurora cluster but not sure if that is instant? Is there a way to stop the old MySQL RDS instance so it can’t be written to? (It as a Multi-AZ and there is no stop)