FIFA host cities will be affected by a special visa registration regime currently planned for May 25 – July 25, 2018. Under the special regime, foreigners will have just 24 hours after arrival to register their visas (rather than the usual seven business days).
This will affect only FIFA host cities (Moscow, Saint Petersburg, Kaliningrad, Kazan, Krasnodar, Nizhny Novgorod, Rostov-on-Don, Samara, Saransk, Sochi, Volgograd, Yaroslavl, and Yekaterinburg). Those staying in homestays, Airbnbs, or hostels should make sure that either their visa sponsor or the registered owner of their accommodation will be able to register them. Not all locations offer the service.
Those staying in regular hotels should have this done by the hotel upon checking in. Those on student visas will be taken care of by the inviting university.
If you will arrive before May 25, you should register on or before May 25.
Be advised that FIFA host cities are also expecting large crowds and increased security measures over these dates.