Ashton Kutcher and Mila Kunis haven't started planning their wedding.

The 'Two and a Half Men' actor and the 27-year-old star are allegedly hoping to tie the knot as soon as possible now Ashton's divorce from Demi Moore has been officialised.

The couple are said to have been secretly engaged for weeks, but only decided to make their commitment public earlier this week when Mila flashed her diamond sparkler during a shopping trip in Los Angeles.

A source told People magazine: ''It won't necessarily be a short engagement. They haven't begun planning the wedding yet.''

The lovebirds first met when on the set of 'That 70's Show' 16 years ago, playing on/off couple Jackie and Kelso, and have been friends ever since.

They put on a public display of affection during the Lakers game this week, kissing and cuddling in the front row, with Mila's engagement rock proudly on show.

Ashton reportedly wanted to keep things simple when it came to choosing the perfect ring.

An insider added: ''It's a simple band with a round diamond. No baguettes, no insets. It's not ostentatious, like a Kim Kardashian ring. She doesn't need a security team with her to wear it. It's a lot like her and Ashton.''