Gillan, who previously starred in Doctor Who episode 'The Fires of Pompeii', will make her first appearance as the Doctor's new assistant Amy Pond in this evening's show.
"Of course I'm nervous," she told The Sun. "Everyone's actually going to watch it now. The time has come."
Gillan also admitted that she is still getting used to her newfound fame, explaining: "I know things are going to change for me - it's kind of already started happening. I get recognised in the street and people want autographs. It's crazy. I'm just a girl from Inverness who got into acting. Now I'm on the biggest show on TV."
Gillan added that she hopes she can keep the role for several more series.
"I know the companions change a lot quicker than the Doctors, so who knows," she said. "I'd like to continue doing it for as long as I can. I've had an amazing time so far."
The new series of Doctor Who begins tonight at 6.20pm on BBC One.