So long, in fact, some of them must have wished they could jump into his Tardis to see how he would portray the irrepressible Time Lord.
But yesterday they travelled from as far afield as Japan and the US to a special premiere of the Scots actor's debut as the 12th incarnation, 17 days before it is to be shown on TV and in cinemas.
Capaldi, Jenna Louise Coleman, who plays companion Clara Oswald, and the sci-fi programme's Paisley-born producer Steven Moffat, got the Los Angeles red-carpet treatment at a special premiere of Capaldi's debut episode, at a Cardiff shopping mall.
The event was attended by 2000 fans, with the Doctor's deadly enemies the Daleks and Cybermen on hand to catch out the unwary.
Capaldi's doctor was glimpsed briefly last Christmas after predecessor Matt Smith's regeneration.
Yesterday Capaldi, 56, who as a teenage actor in Bishopbriggs tried to set up a Doctor Who fan club, said: "It's every young boy's dream to be Doctor Who. If I could go back in time and speak to you, my younger self, I'd tell him keep drawing those comics of yours and keep writing to the BBC."
Capaldi's darker edge was seen in the debut episode, titled Deep Breath, which was shown at the ticket-only event in Wales and last night at another gala premiere at the British Film Institute in London.
Moffat said: "I've been to some big premieres in LA, and the turnout and response here has been even better than those."
Coleman added: "We can't wait for people to see the new series. The new Doctor is going to be darker than before and there are lots of surprises in store."
Mother-of-two Kristan Fedderson, 47, from Chicago, scrapped a holiday to France to be in the Welsh capital for the event. She said: "My husband Brett and I have been fans of the show since the 1980s. We couldn't believe we were going to be in Europe when the premiere was happening, so we knew we had to come across to Cardiff.
"Our daughters have become big fans of the show as well."
Kat Max, 40, of Penarth, south Wales, came as a Dalek despite missing out on tickets. She said: "We've been excited about this for weeks. The whole family loves the show, although I think I'm more scared of the monsters than the children."
Local fan Necia Eades has been watching the programme since she was 18, when the First Doctor, William Hartnell, starred.
The 68-year-old said: "Peter's a great choice because he's the fans' choice. He's just like one of us and the way he has been today shows it. He's signed so many autographs and given loads of his time to speak to people."
Guest stars in the new series, which begins on Saturday, August 23, include comedian Frank Skinner, Ben Miller and Keeley Hawes. There is also a comeback for the popular reptile-like Silurian Madame Vastra.
Moffat urged fans to keep one of the new episode's biggest surprises secret, but that seems unlikely with Twitter.
At a question-and-answer session, Capaldi was asked what his alter ego, spin doctor Malcolm Tucker from Armando Iannuci's Thick of It satire, would think of the Doctor.
He replied: "He would probably be jealous. I think he would be incredibly envious that me, his alter ego, had got such a big gig."
He also suggested the relationship between his Doctor and Clara would be different to Smith's flirting. Capaldi said the pair still loved one another, but it went beyond romance.
Capaldi, announced as the new Doctor a year ago, had not realised he was the producer's first choice. He added: "I didn't know this at the time but I was first on their list and the only person they intended auditioning."
The show was brought back in 2005, 16 years after the original series was axed, but Moffat said there are no plans for a 10th anniversary special next year.