Photos published by the Daily Mail showed the sprawling property, which sits on a 2.8ha lot, decorated with tubs of flowers and strings of fairy lights before the main ceremony, which will take place at Sea Crest Nursery in Goleta.
Security has been intensified, with reports Gomez is spending around US$300,000 ($519,000).
A source quoted by the Daily Mail said Taylor had flown in from Kansas City earlier in the day on Friday, travelling without her fiancé, American football star Travis Kelce, 35, who is preparing for the Kansas City Chiefs’ NFL game against the Baltimore Ravens.
Taylor, who once promised Gomez she would act as her flower girl, has been a long-time friend and will be among the 170 guests at the nuptials.
Most of the wedding party are staying at El Encanto, a Santa Barbara resort owned by Tinder co-founder Justin Mateen, where rooms start at US$1000 per night.
Other attendees include Paris Hilton.
Before heading to the rehearsal dinner, Steve Martin, Short and Rudd were seen socialising at El Encanto.
Martin co-created Only Murders in the Building, which has run for five seasons and features himself, Gomez and Short in lead roles, with Rudd guest-starring in recent seasons.
Gomez and Blanco confirmed their engagement in December last year with an Instagram post captioned: “Forever begins now.”
The singer also displayed her marquise-cut diamond ring in accompanying photographs.
The couple, who first collaborated in 2019 on the track I Can’t Get Enough, grew closer during work on Gomez’ 2023 hit Single Soon.
They later made their red-carpet debut at the 2023 Emmy awards.
In February this year, Blanco told Apple Music’s Kiwi host Zane Lowe about his relationship with Gomez: “I’d have to say overall it’s the safest that I feel and it’s been really lovely and I’ve only grown through it, so it’s awesome.”