Thursday was the first day that same-sex couples could obtain marriage licenses in the state of Washington, and one church is planning a group ceremony for Sunday, at which thirty couples will wed.

The Seattle First Baptist Church, which has been performing same-sex commitment ceremonies since 1979, will marry thirty couples in a group wedding on Sunday, the Huffington Post reports.

Pastor Craig Darling, of the First Baptist Church, said that he is expecting 900 guests to turn up to Sunday’s ceremony, and that it will be inclusive of all faiths.

Marriage certificates have been available to couples since Thursday at 12.01am, however the state of Washington has a three-day waiting period, so the first time the couples can marry is Sunday.

One of the first couples to be issued a certificate, Pete-e Petersen, 85, and Jane Abbott Lighty, 77, have been in a relationship for 35 years. According to CNN, the pair met on a blind date in 1977 and previously assumed they would die before being legally married in the state.

During the ceremony, two choirs will perform, and couples will exchange love-letters during the service. Pastor Darling said:

“We’re very excited that, for instance, Pete-e [Petersen] and Jane [Abbot Lighty] we performed their covenant ceremony several years ago, and at the time none of us believed this day could be here,” Darling said. “It’s so exciting to know that they’re going to be legally married and affirm the love they have shared for so long.”

Washington made history last month as one of three US states where marriage rights were extended to same-sex couples by popular vote, joining Maryland and Maine in passing ballot initiatives.

Counties across Washington have been opening extended hours, in order to accomodate the huge demand for marriage licenses, now that the law is in place. Seattle City Hall is set to host 142 marriage ceremonies inside its lobby on Sunday.

Last week, Washington State’s Department of Health also said it is currently reviewing the text displayed on marriage certificates, with a view to bring it in line with recently introduced equal marriage law.