Right now you don’t want to do a migration. You want to support both on the front end.
You’ll need to talk to your ISP to ensure that they support IPv6 (not all of them do). You’ll want to check with your router/load balancer company to ensure that the software and hardware that you are using support IPv6.
What some people are doing is simply putting IPv6 on the front end, and using NAT/PAT to change those IPv6 IPs back to IPv4 on the inside.