The company said additional heavy drilling fluids are necessary for the process and it is now awaiting delivery.
Once taken the core samples will be analysed to determine the oil bearing horizon and quantify the discovery, Roxi said.
Chairman Clive Carver said: "The board of Roxi remains excited about the discovery and looks forward to updating the market further in due course."
Roxi shares soared almost 300% earlier this month with the news of the A5 discovery, after the company announced it had encountered oil and gas shows at depths below 4,300 metres. It saw the exploration share trade as high as 15.75p from 4p.
Today on AIM, Roxi was down 1.12p or 7.89% at 13.12p.