"But it's best not to think about it. It's best just to take it one show at a time."
Sheeran will begin his tour in Perth, performing the first concert at the new Optus Stadium on Friday, but says he is not nervous.
In a world first, the Grammy winner will also offer exclusive merchandise to Australian fans through Divide pop-up stores.
Sheeran will be joined on tour by Missy Higgins and says he likes to have support acts who have influenced him.
"It's a bit awkward, everyone keeps telling her that I had a crush on her," he laughed.
"It was a long time ago and the interview was a long time ago as well. I didn't think I'd actually meet her."
Sheeran has been fishing in Perth during this visit, although he failed to catch any, and says he wants to avoid being stuck in a hotel room.
But he has no plans to add a quokka tattoo to his koala tattoo, which he received on a previous visit to WA.
"I've already got my Perth tattoo, I think if I was to get (another) one I'd get 'Brisvegas' or something," he quipped.
The best-selling recording artist of last year promises he will perform his most popular hits.
"The show differs every night but the songs that people want to hear, they will hear ... unless they're into really niche tunes from like 10 years ago."
But Sheeran says he is surprised when he plays a "random" album track and everyone still knows the lyrics.
Some eager fans have already begun camping at the stadium, with one group of friends planning to attend every show.
Sheeran says he hopes they enjoy the 18th concert as much as the first.
The 27-year-old also maintains he will "slow down" when he has children.
"I'm not going to spend two years at a time going on tour. I'll tour for three months a year like normal people do," he said.
"I'm never going to stop making music but your priorities shift."
• Sheeran will perform in Perth, Adelaide, Melbourne, Sydney, Brisbane, Auckland and Dunedin.
ED SHEERAN'S RECORD-BREAKING TOUR
• Highest ticket sales for a single concert tour in Australia
• Highest ticket sales for a single concert tour in New Zealand
• Biggest stadium tour of Australia and New Zealand
• Venue record for most number of shows on one tour at Optus Stadium, Etihad Stadium, Suncorp Stadium and Forsyth Barr Stadium
• Venue record for highest attendance for a single show at Optus Stadium, Suncorp Stadium, Mt Smart Stadium and Forsyth Barr Stadium.