For 19-year-old American Jacobsen it was his first taste of Superbike action aboard the team's GSX-R1000 while Brookes was in blistering form, despite the low spring temperatures.
Brookes said: "It was great to be back out on track and despite coming from 30-degree heat at home in Australia to single-digit stuff here at Kirkistown, we completed a successful opening day.
"I got within a few tenths of my quickest-ever lap-time around here, despite the cold conditions and using our new Ohlins Suspension for the very first time, so I'm pleased with how it all went."
Jacobsen commented: "There's a lot to learn as there are so many things on the Superbike compared to the Superstock bike, and it will take a couple of tests to get 100 per cent comfortable, but all in all it was a progressive day.
"I was surprised how smooth and usable the power was on the Superbike and by the end of the day we were doing consistent lap times. I'm pretty pleased how we have started and I'm looking forward to day two on the big Suzuki."
Ryuichi Kiyonari is looking ahead to the official test at Donington Park after a successful shakedown on the Samsung Honda at Cadwell.
The Japanese, chasing a record fourth title in 2013, participated in a two-day test with team-mate Alex Lowes.
“We have a better idea now of where to start for the next test at Donington Park and I felt more comfortable back on the Superbike," he said.
Lowes, who finished as the leading Honda rider in 2012 on the WFR machine, said the test 'couldn't have gone any better'.
“I am really chuffed with the two days we have had at Cadwell Park and I have left feeling really happy,” he told the British Superbike website.
“The Samsung Honda has so much potential and we did some really good work on engine braking today which was a really good step forward."
Meanwhile Michael Rutter hopes to be fit in time for the opening round at Brands Hatch in April after breaking his leg during a test crash in France on Sunday.
The 40-year-old suffered a fracture at the base of his tibia in testing with the Honda TT Legends EWC team. The 40-year-old will compete in the series for Quay Garage Racing under the Bathams banner with Tommy Bridewell.