On 1 October '98% of England' was offering access to extended hours GP appointments, NHS England told GPonline - leaving general practice just short of the target.
NHS officials originally planned nationwide access to extended hours GP appointments - offered outside core hours of 8am to 6.30pm Monday to Friday - by 31 March 2019.
The deadline was brought forward by six months earlier this year in a bid to ease pressure on the health service by increasing availabilty of appointments in primary care - a goal NHS England said had been achieved.
An NHS England spokesperson said: 'With 98% of England offering weekend and evening GP appointments, we are well on track to hit the 100% target, originally set for March 2019, but brought forward to make more appointments available this winter.'
GP leaders hailed the 'hard work' practices had put in to expand extended hours coverage, but warned that the extra appointments may simply drive up demand and argued that extra funding would be better spent on improving care within core hours.
NHS England has estimated that extended access to primary care services will provide an extra 9m appointments per year. It plans a national campaign to advertise availability of appointments outside of core hours ahead of this winter.
Under the extended hours access scheme, patients may not be offered appointments with their own named GP or practice, but will have access to a GP in their area outside normal opening hours - in addition to existing out-of-hours services.
GPC chair Dr Richard Vautrey said: 'It's only been possible to get to this stage with the hard work of GPs working together to deliver this extended service. However these services often provide a wider opportunity for patients to make appointments rather than reducing overall demand and there is limited evidence that this will materially reduce the numbers of patients attending A&E.
'We have consistently argued that this important resource, both funding and workforce, would be more effectively used with a greater focus on core hours. This is when most patients want to be seen. More investment here would provide greater help in reducing the current workload burden on practices.'
GP practices faced intense pressure throughout last winter as a spike in flu cases and the cancellation of thousands of elective hospital procedures drove up demand for appointments in primary care.
The BMA warned earlier this month that GPs would be 'stretched to the limit' through the coming winter - highlighting data that reveal pressure on emergency services through summer 2018 was higher than in five out of the past eight winters.
Dr Vautrey said last month that local practices should be able to use the extra capacity delivered through extended hours schemes flexibly to 'support patients struggling to get appointments with their surgeries during the day'.