Brezhnev ousted Khrushev in 1964. What method do you use to determine when someone consolidates power? One way to check for power consolidation for X is this: X stages a bloodless coup and removes the head of state/government and places himself in his place.

If you think pre-Brezhnev's USSR was doing well, compared to free market economies of the time, you would be sorely mistaken (which was part of the reason Khrushev was removed). The best USSR could do was meaningless industrial output metrics (oh, we made just a whole LOT of pig iron). Of course without an integrated economy such output is meaningless. See also: output targets in China during the Great Leap Forward. USSR was an economic basketcase during the best of times.

Unrelated anecdote: I once got in trouble (e.g. parents in the principal's office) as a young child for laughing on the day Brezhnev died.