Panic no more!
I received my fan ID a few months ago but received a text and email today linking me to an electronic version of my Fan ID to print out and take with me. I assume that this will be the same for everyone.
This finally puts to bed the panic amongst folk about the delivery of their physical fan ID. You can get in the country and attend games with a printed out version. They Russian authorities clearly know now that not everyone will receive theirs in time for attending!