The forward - who was again playing as a trialist as the Light Blues wait for a transfer ban to end on September 1 - supplied two goals in a 6-0 win.
Daly has put in plenty of effort this term but, until now, had been frustrated in his attempts to find the back of the net.
McCoist said: "I'm delighted for him.
"Jon got his two goals and it was just rewards for the way he has been playing.
"We've always felt - and Jon has too - that the goals would always come.
"That's certainly been the case and I hope he can add to that tally."
Lewis Macleod, Andy Little, Robbie Crawford and Nicky Law were also on the scoresheet.
Ian Black started the match despite a week of dominating the headlines.
The midfielder has been charged by the Scottish Football Association with alleged breaches of rules on gambling.
McCoist was pleased by Black's display and the response of Gers fans at the Excelsior Stadium.
He said: "We feel he's started the season really well and Ian's performance tonight certainly didn't surprise me.
"I thought the Rangers fans would support one of their own and I thought the support was fantastic."
Results on the pitch may be positive so far this term but have played out against the backdrop of a bitter power struggle at Ibrox.
McCoist said: "I obviously want stability throughout the club.
"We feel we are making slight improvements on the playing side of things and we have certainly strengthened the squad.
"Hopefully off the park we can have a little bit of stability too.
"I think the fans deserve that and the board of directors know and appreciate that.
"I'm very hopeful in the next two or three months we can get stability on and off the park."
Reflecting on the heavy loss, Airdrie boss Jimmy Boyle said: "It was a real lesson.
"Our start was wonderful and we were in their faces for the first 20 minutes.
"We should have made a couple of chances count.
"This was a real lesson in finishing for our players."