According to the note of Russia's Ministry of Transport, from 19/12/2013, sales for long distance trains start 45 days prior to departure. Starting from December, 2016 to improve the quality of service Russian railroad release tickets on sale 60 days in advance. Currently sales for 3rd class and seating carriages are stopped for departures after January 1st, 2018.
At the moment Federal Passenger Company is waiting for new prices for 3rd class and seating carriages to be decided by the Ministry of Transport of Russian Federation. Sales will start as soon as new prices are fixed but no later than November, 17th.