Actually it appeared a little before 1991, in 1989. There was first Internet connection to Finland in Demos institute (their demos.su domain is still operational) and I can remember reading their Usenet posting about communist coup d'etat in 1991.
In 1991 they played with local TCP/IP in Moscow, in 1992 started to make dialup calls to Finland with SLIP instead of pure UUCP. Only in 1993 several permanent TCP/IP links from Russia (Demos, SOVAM Teleport, etc) to the West were finally established.
Please also check detailed history: http://ru.arf.ru/Hrono/index.html
12-19 August 1990.