Figures show that more than half of GP surgeries in Scotland are now offering appointments outside normal opening hours, in spite of the BMA's opposition to the plan.
The Scottish government launched the policy in April, and in the four months since then, 51% of practices, serving almost 3 million patients, have extended their opening hours by an average two-and-a-half hours a week.
Health Secretary Nicola Sturgeon welcomed the figures, but called for more practices to take part.
"We are encouraged that just four months into the scheme so many GPs are participating," she told the Herald newspaper. "There is little doubt the public back extended opening hours and I would urge those GP practices still to enter the scheme to get involved."
Ms Sturgeon added that the Scottish government had made available increased resources for extended hours, which practices could apply for.
However, the BMA said that the extended hours were not benefiting the patients the policy was aimed at – full-time workers – as other patients were taking up the extra slots.
"It is not going to improve the health of Scotland because it is the same people who come during the day – they just come more," said Dr Dean Marshall, chairman of the BMA's Scottish GPs Committee.