Video report by ITV News Correspondent Neil Connery
Tuesday marks the first day of decriminalisation of same-sex marriage in Northern Ireland, after attempts to halt the move failed on Monday.
Additionally, abortion also becomes legal in the country on the same day.
The legislation was passed by Westminster in July and would take effect by October 21 if the Northern Ireland Assembly and Executive had not been reformed.
Stormont has not met in three years but the DUP tried to get the Assembly to sit on Monday in order to thwart the new laws but now all parties attended.
DUP leader Arlene Foster called it "a shameful day" for Northern Ireland.
The first same-sex marriages in Northern Ireland are likely to be taking place by Valentine’s Day 2020, according to the Secretary of State.
Julian Smith said he also plans for the new legal framework for access to abortion services in the region to be in place by March 31.
Mr Smith told the House of Commons on Monday that consultation will open “very soon”.
“A new legal framework for lawful access to abortion services in Northern Ireland will be put in place by March 31 2020 in line with the 2018 UN Cedaw (Convention on the Elimination of Discrimination against Women) report.
“I will be consulting on the new framework very soon,” he said.
“On same-sex marriage and opposite-sex civil partnerships, regulations are to be made no later than January 13 2020.
“There are two key areas we are going to consult on. How to allow for religious same-sex marriage ceremonies, and also the issue of conversion from civil partnership to marriage and vice-versa.”
He added: “At the latest, the first civil same-sex marriages will take place on the week of Valentine’s Day 2020.”
Mr Smith said the Northern Ireland Assembly “can influence” but was firm that the law has changed.
“We need to be clear that the law from tomorrow has changed across those two areas, and we can, obviously we will hear the views of the Assembly, and we will work with them, but the law, from tomorrow, has changed,” he said.