The countdown began on Friday to the moment at midnight when same-sex marriage becomes law in England and Wales, the final stage in the long fight for equality for gay men and lesbians.
Several couples are vying to make history by saying "I do" in the first few minutes of Saturday morning, when the historic marriage law passed by parliament last year comes into force.
Many more plan to exchange vows in the hours that follow, including one couple who will perform almost the entire ceremony -- barring the legal declaration -- in song for a television programme entitled "Our Gay Wedding: The Musical".
Civil partnerships have been legal since 2005 and marriage brings no new rights -- the ability to adopt, for example, was introduced in 2002. But campaigners demanded full equality with heterosexual couples.
"We didn't want to get married until it was a marriage that my mum and dad could have, that other men or women could have," Teresa Millward, 37, told AFP.
She is marrying her girlfriend of 11 years, Helen Brearley, in Yorkshire on Saturday morning. Both will be dressed in cream, and Millward's father will walk them both down the aisle of the register office.
Gay marriage was championed by Prime Minister David Cameron's government, and a rainbow flag will fly over government offices in London all weekend in celebration.
Although members of Cameron's Conservative party and the established Church of England opposed the move, it has support from the majority of the public.
The law is the final victory in a long battle stretching back to the decriminalisation of homosexuality in England in 1967.
"Finally, after years of campaigning, any couple who wants to get married can get married," said Deputy Prime Minister Nick Clegg.
"Together we've made our country a place where we celebrate love equally, gay or straight -? and for that reason we should all be raising a glass."
- Sending a message abroad -
The Church of England had opposed same-sex marriage, insisting weddings should only take place between a man and a woman, and secured an exemption from the new law.
The House of Bishops last month also warned clergy they should not bless married gay couples.
But Archbishop of Canterbury Justin Welby, the leader of the world's 80 million Anglicans, indicated on Thursday that the Church would no longer campaign against the issue.
"I think the Church has reacted by fully accepting that it's the law, and should react on Saturday by continuing to demonstrate in word and action, the love of Christ for every human being," he told the Guardian newspaper.
In Brighton, Neil Allard and Andrew Wale hope to be the first gay couple to get married by exchanging vows at one minute past midnight in the picturesque surroundings of the Royal Pavilion.
Posing for media photographs earlier this week, Wale remarked how positive the reaction to their wedding had been, with passers-by offering "lots of smiles, lots of warmth".
"We become even more aware of how lucky we are to live in a comparatively tolerant part of the world," said the 49-year-old writer and theatre director.
In London, Peter McGraith and David Cabreza are also bidding to make history by marrying at midnight in front of friends and family, including their two adopted sons.
The couple have been together for 17 years and hope their wedding will send out a message around the world.
Fifteen countries have legalised gay marriage and another three allow it in some areas, but homosexuals remain persecuted in many parts of the world.
"There's a lot of gay men and lesbians around the world who are not invited to the party," McGraith told AFP.