Hamilton and Button have three further track testing sessions to test the MP4-26
McLaren insist their new car will not suffer early-season teething problems - despite missing the first winter testing session for the 2011 season.
The new MP4-26 will be launched on 4 February, a day after the first official testing session ends in Spain.
It means McLaren have three chances to test its reliability before the opening grand prix in Bahrain on 13 March.
"We are reasonably confident we can get all the reliability we need," said McLaren engineer director Paddy Lowe.
Team principal Martin Whitmarsh said the decision to delay the testing of the MP4-26 was to give drivers Jenson Button and Lewis Hamilton "the best possible package" for Bahrain.
It means the British team will head to the first of four winter sessions at Circuit Ricardo Tormo in Valencia between 1-3 February with a standard 2010 chassis and a limited number of updates, while rivals Red Bull and Ferrari will unveil their new models for on-track testing.
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Red Bull did not test the constructors' championship-winning RB6 in the first winter testing session of 2010 and suffered early-season problems when Sebastian Vettel lost the lead at the Bahrain Grand Prix because of a spark plug problem, finishing fourth as a result, before retiring in the following race in Australia with a wheel problem.
But Lowe remained optimistic that McLaren's rigorous in-house testing will ensure there is no risk of major teething problems for the first race of the season.
"It's always a balancing act between how much mileage you are going to cover from a reliability issue and from a set-up point of view working with the new car," he said.
"Then you are trading against development time in the lab, wind tunnel and office. In terms of reliability impact, more and more work is done in the lab, typically on a dynamoteter (a device which measures force), to prove the major mechanical systems on the car.
"We are more confident that we can hit the ground running with a reliable package without doing thousands and thousands of kilometres on the track. You always learn something from mileage but it's a trade."
McLaren finished second in the constructors' title last year
This season's cars will adopt a number of technical changes including the adoption of moveable rear wings as well as the return of the Kers power-boost system, which had been voluntarily suspended last season, as used by McLaren in the 2008 season.
Lowe believed the new rules introduced by world governing body FIA make it difficult for McLaren to gauge their development against their competitors.
"It's a stressful time for all the engineers from this point onwards and first qualifying at the first race where you really understand where you are," he added.
"Everybody has no reference to what level of absolute performance is needed.
"We are confident with what we have done. The team have worked well over winter and we think we have a good car, but that will probably be true of our competitors.
"We have taken some estimates as to what level of performance we need to be at and we are on track for that. But time will tell whether that is sufficient."