Bayern, who clinched the Bundesliga title with six games to spare on Saturday, announced the retirement of the 67-year-old in the same news release in January that confirmed the arrival of the hugely successful former Barcelona coach for next season.
Annoyed by the way the club tried to force his retirement, Heynckes, nicknamed after light bulb maker Osram for the way his head turns red when agitated, said he was the only one who would decide when to retire.
"This is a decision I will announce myself, we still have a few months' time," Heynckes said, refusing to tow the club line on the issue.
"Those who know me, know that I am very ambitious and passionate not to change anything now. My aim is to win the Bundesliga."
Since then he has unleashed an unstoppable Bayern team in the Bundesliga, racking up 11 consecutive wins since the mid-season break, including Saturday's 1-0 victory at Eintracht Frankfurt, and conceding only seven goals.
He also steered them into the German Cup semi-finals and the four-time European champions are also on the brink of a Champions League semi-final spot after beating Juventus 2-0 in the first leg of their quarter-final this week.
The Bavarians are on track for an unprecedented treble by a German club and fans are already speculating that Guardiola may find himself in a position where it would be hard to improve on this season at the success-driven club.
Ex-Borussia Moenchengladbach striker Heynckes, who coached Bayern to the 1989 and 1990 Bundesliga titles in his first spell and won the Champions League with Real Madrid in 1998, had a second brief stint at Bayern in 2009 when he replaced the sacked Juergen Klinsmann near the end of the season.
A close friend of Bayern president Uli Hoeness, Heynckes, who won the 1974 World Cup and the 1972 European Championship as a player with Germany, returned for the 2011/12 campaign.
In his first season back at Bayern he had three second-place finishes in the German Cup, league and Champions League.
He has already topped that this season.
A pragmatist and a man of few words, Heynckes, who this season broke the 1,000 Bundesliga games mark as player and coach and is still third on the league's all-time scorer list, feels most comfortable on the training pitch among his players.
He has restored Bayern's confidence after a turbulent time under predecessor Louis van Gaal and it has now paid dividends.
Bayern's Bundesliga triumph marks the end of a two-year reign by Borussia Dortmund and gives the Munich side their first trophy of any kind since 2010.
Heynckes can leave at the end of the season knowing he did it his way.