It's been three months since Matt Lanter proposed to longtime love Angela Stacy, and since then, the couple has been mapping out every aspect of their big day.

"We think we got a date nailed down, but we're still trying to figure out details," 90210 star Lanter, 29, tells Celebuzz. "I never knew how much f-cking details go into a wedding. Oh my god!"

Though prepping for their wedding has been mostly "fun," Lanter admits the process has also been daunting. "You're trying to think about how everybody else is going to have fun, and you kind of forget about yourselves, which is the whole idea of wedding," he explains. "It's an interesting little dynamic."

Stacy -- who calls her fiance "my very best friend and the love of my life" on Twitter -- is taking charge of most of the planning, according to Lanter. "I'm trying to help as much as I can in between watching football and whatever other things I'm doing on the couch," he laughed to Celebuzz.

When Lanter popped the question in June, a source told Us Weekly he "picked out and designed the ring himself. It's gorgeous!" This will be the first marriage for both Lanter and Stacy, who hail from Ohio and reside in L.A.

The fifth season of 90210 premieres October 8 at 8 p.m. EST on The CW.