Finally! There is an official confirmation from FIFA that ticket sale will start on 14 September. There will be several sales phases with different procedures. You will find some details here.
Also Kaliningrad Guide Blog will cover all possible topics about visiting Russia and Kaliningrad for the 2018 World Cup. Feel free to ask any related questions in the comments bellow.
So far we have the following qualified teams: Russia as Host, Brazil, Iran, Japan, South Korea, Saudi Arabia, Mexico and Belgium.