It was still a baptism of fire for the 38-year-old, who had never previously managed in the Premier League, after predecessor Eddie Howe stepped down.
Jaissle insists friend Thomas Tuchel “didn’t need to warn” him about what was coming in the top flight, but he had just three weeks to prepare for the visit of Liverpool on the opening weekend and the squad was in flux.
Captain Bruno Guimaraes was about to follow Anthony Gordon and Sandro Tonali out of the exit door and complete a £75m move to Arsenal at the time.
Although Newcastle would end up making eight signings, they were all aged 24 and under as the club went from having one of the most experienced sides in the Premier League to the youngest almost overnight.
It was a huge amount of change in a short space of time.
There have also been a spate of injuries to key players, but Jaissle has only lost one of his opening seven matches in all competitions, a chastening 4-1 defeat at Leeds United.
“I think there were elements in games where we saw a lot of the things we were looking for,” he says. “There were also phases in games where we were not happy and satisfied, so there’s still a lot of potential that we can improve.”
Jaissle accepts it has been “tougher than expected” to “get stuff into the players’ heads” given pre-season was “so short and packed with friendly matches we couldn’t change”, adding “but considering all these things, we’re doing good”.
He remains convinced that his aggressive style of play and so-called vertical football will “work anywhere”, even if this team is clearly still a work in progress at such an early stage of his reign.
Newcastle have made the most errors leading to shots (12) in the Premier League this season while, at the other end of the field, Jaissle’s clinical side have only averaged little more than three efforts on target per match in the top flight.
It feels like there will be ups and downs throughout, given the age of the side, but Jaissle has been struck by the backing of supporters and has quickly settled into life on Tyneside.
He moved out of a hotel into a new home earlier this week and has ventured into the city to sample a handful of restaurants – but only to celebrate wins.
Following the 2-1 victory against Hull City at St James’ Park last time out, he even paid for a supporter’s birthday meal.
“I really love the fans and the people here,” he adds.