When I look at the official ONI values from 1950 and onward, I find at least two cases aside of 1986/1987 when El Niño started this late or later in the year that had an ONI>1. The episodes in 1968/1969 and 1994/1995 both had a maximum ONI=+1,1. If one want to be generous, we might also count the the prolonged El Niño in 2014-2016 to this category too. Hope you can clear this out :) With best regards!