Hawn said the pair are excited to share the moment with their close friends and loved ones -- including her daughter, Kate Hudson, Reese Witherspoon and The Hateful Eight director Quentin Tarantino, who are among a number of stars set to pay tribute to the timeless couple.
"We're gonna have our friends there, old friends, it'll be very nice," she shared. "It's been such a long time since we ever did anything like this. People look and say, 'You mean you don't have one yet?' No we don't, actually."
Hawn and Russell began dating in 1983 while shooting their romantic WWII period drama Swing Shift, and have been together ever since. However, the pair have famously never tied the knot.
"It's really funny, you know, because we never got married, so this is really kind of an interesting little ceremony," Hawn said with a laugh.
After partying at the Playboy Club, Russell explained, he and Hawn snuck off to a house that she was renovating at the time, and made themselves comfortable.
"We eventually found our way upstairs. We were looking around at imaginary furniture, and we are in the imaginary bedroom now, and we're realistically having sex, when the police walked in, because we had to break into the place to get in," Russell recounted. "So the next thing I know there's a flashlight, and Goldie and I are like, 'What?'"
According to Hawn, however, the real story isn't quite as salacious as it sounds, and despite it being their first technical date, the pair had been flirting for some time.
"We had a lot of foreplay before, because we were making a movie together and we were feeling [each other]," she explained. "I think we had been thinking about it a long time."
"And I don't want to blow the story up, but what actually happened was, afterwards we finished and it was great and were lying on the floor, then the police knocked on the door," she added. "So they didn't exactly catch us in the act."
Hawn said she has no regrets about that date, however, and she's not embarrassed by the story.
"I felt great [about it], why shouldn't I? He was hot, great and really fun," Hawn exclaimed.
"It was special for me," Hawn said of the heartwarming encounter. "I was looking forward to meeting him a lot and what I feel from him is very pure. It's not about anything, it's not just a fan thing. It was so deep and pure and I just, I don't know, I felt very close to him. So I got emotional too."