WI Stalin had not invaded Western Poland, the Baltic States and Finland early in WW2.
I assume that Finland does NOT ally with Hitler, I think that this helps Leningrad,
I do not know how much difference it makes to Barborossa overall.
Obvously Poland still falls to Hitler, I think it is possible that the Nazi war machine will be more damaged by this victory.
I do not know if that delays events in 1940