The striker - scorer of a 31-minute hat-trick in the victory over Bristol City - had contributed four assists previously during Blues unbeaten start to the campaign.
Such an integral player for Blues in the way they play, it was only a matter of time before The Don notched.
"I wasn't stressed about that at all," he said.
"We have been playing well and winning games. And I have been contributing to the goals as well.
"I have been playing well, we have been getting the points in the board. There's not been too much to worry about, to be honest.
"I got the goals Saturday, which is an added bonus. But the three points was the main thing."
Donaldson second Blues hat-trick was completed with a penalty.
Regular spot-kick taker Paul Caddis invited Donaldson to step up at 12 yards after Jon Toral was impeded by Aaron Wilbraham with the score on a knife-edge at 2-1 in the 41st minute.
"I could hear Cotts whispering to Caddis 'let him have it', as I was on my hat-trick.
"As I got closer, I managed to make a little eye contact with him and I gave him a little nod. He said if you want it, you can have it.
"Of course, he's the penalty taker and I respect his decision. Luckily he was feeling quite generous and I was able to get my hands on the ball.
"I had every confidence and belief that I would score."
Donaldson also had the ball in the back of the net after the break, when he instinctively nodded in a deflected Demarai Gray shot that looped up into his path.
"The boys have looked back at the footage and told me it was onside.
"Obviously we won the game and I got the hat-trick, but you expect the officials to get things right most of the time and give the benefit of the doubt to the strikers.
"So it was a little disappointing I didn't get four. But I can't complain too much."
Blues got their tactics spot-on to extend their unbeaten run, stretching back to last season, to 11 games.
Bristol began with a back three and Blues deliberately got Gray and David Cotterill advanced to exploit the space behind the wing-backs. Often, Bristol's centre-halves were isolated had to contend with them running at them one on one.
That's how Blues first goal came, in the 10th minute, when Gray had Liam Moore backpedalling and crossed for Cotterill to set up Donaldson inside the six-yard box.
"We wanted to push them on high up the pitch," said Donaldson.
"With their formation, it definitely worked for us.
"It was a 3-5-2, we're not quite used to playing against that formation, but we had analysed them a lot and watched a few videos on their games.
"The manager wanted the players to push on and cause them a few problems going back towards their goal. The first two goals came from that."
Donaldson's second goal was steered in from a delicious Toral pass, from the right, after he got in and attacked the backline.
"That's been coming.
"Games before, he had been playing those balls in and it hadn't quiet happened.
"We see in training every day the technical ability of the players, it's unreal. Jon has got so much ability.
"It was a great ball into the box and hopefully my legs were going to be long enough to get on the end of it - and they were."