"It's just gone crazy," he said, adding that in his experience of 30 years in retail, the busiest days of the year were the 24th and the 26th.
"That hasn't changed. What has changed is that Christmas last year was on a Friday so everyone finished work on Thursday and it was a mad rush to shop on the Thursday afternoon. This year it's on Sunday, so Friday and Saturday are just going to be crazy nights. We've been busier than last year already, but we're expecting this massive double hit."
Mr Hill said the opening of the plaza's food court was also having a significant effect on foot traffic and sales.
Bayfair Shopping Centre manager Steve Ellingford said traffic had been picking up in the past few days.
"We're expecting a strong run into Christmas, with late night trading, and Kmart opening 24/7. I think people will spend right up until Christmas and they'll be straight back out and into the Boxing Day sales. It just does not end."
Bethlehem Town Centre manager Andrew Wadsworth said that spending was expected to be up on last year, even putting to one side the expected impact of Kmart, which opened earlier in the year.
"It's been busy all month, but yesterday was notable for it getting very busy," he said. "I'm expecting Friday and Saturday to be exceptional, as well as Boxing Day. We will probably get to mid-January before it dies off. Our retailers are very happy."
Mount Main Street manager Ingrid Fleming said she felt low mortgage rates and the recent increase in residential property values were encouraging retail spending.
"The Mount is a holiday destination and a lot of people love to shop in their holidays because they don't get a lot of time often when they're working. We are expecting that to continue through the holiday period."
Sally Cooke, spokeswoman for central business district retail organisation Mainstreet Tauranga, said the feedback from its members was positive for the Christmas period.
"They seem quite buoyed up," she said.
"We always want to see a really healthy trade going into Christmas because it's such an important time for our retail sector. And the whole Boxing Day sale trend is just getting bigger and bigger every year. I think some of the Boxing Day sales are pretty close to rivalling the pre-Christmas shopping days, so that's good for the sector because spending flows on beyond Christmas."