"I've spoken with Jobe over the last few days," the 19-year-old midfielder said. "He asked, 'What's going on with you?' And I told him I couldn't say for sure yet either.
"But we talked a lot. And he kept saying the whole time that I should come to Dortmund. I'm glad we'll be playing side by side now."
Borussia Dortmund moved for Nwaneri after new signing Giannis Konstantelias suffered a serious knee injury, with the German club needing to strengthen their attacking options before the window shut.
"As soon as I heard about Dortmund's interest and we had a meeting, everything moved very quickly," Nwaneri said. "Within just a few hours, there were advanced talks going on behind the scenes. So, as soon as I found out they were interested, I was ready to make the move."
The switch is a straight loan with no purchase option for Dortmund, but Arsenal have inserted a recall clause allowing them to bring Nwaneri back in January if they are unhappy with his game time or need him back in north London, according to Fabrizio Romano.
Sky in Germany report that Dortmund would incur no cost if Arsenal exercise the clause, though the Premier League club must notify their Bundesliga counterparts in good time, with the option itself carrying an expiry date.
It would not be the first time Dortmund have had a player recalled mid-season. Chelsea activated an almost identical clause in January to cut short Aarón Anselmino's loan at the club, ending the Argentine defender's spell in Germany early.
Nwaneri will get an early chance to test himself against his parent club, with Dortmund drawn against both Arsenal and Aston Villa in the Champions League league phase this season.
"It's much easier now," he said of adjusting to life away from England, having also spent six months on loan at Marseille last term. "The first time, you're really leaving your comfort zone. It's just uncharted territory. But now I'm more relaxed, more open, and mentally better prepared. I know what to expect by now.
"Both [the Emirates and Villa Park] are definitely special places. Quite a few teams in England find it challenging to play there. The atmosphere is great at both stadiums. I'm sure they'll be two really good matches. We have to be ready."
"I'm here and I'm going to fight for my spot on the team," Nwaneri added. "I'm going to give it my all – as much and as well as I possibly can – for the fans. We'll see what comes of it. I'm ready to fight and sacrifice myself for the team."