Do I Need To Indicate The Exact Dates Of My Visit To Russia?

If your exact travel dates are not yet settled, it is always a good idea to obtain a tourist invitation for a longer period than you actually plan to stay in Russia. Then you can get a visa for the same period and travel between the dates with no problem. You cannot enter earlier or overstay your visa but you always can enter the country later or/and leave it earlier than originally planned.