Boeing has started offering the 777X to airlines and leasing companies, the last step before a formal launch event.
The new talks with customers cover "additional technical, pricing and schedule details" about the possibly stretched, re-engined and rewinged update of the 777 series, Boeing says.
"We are aggressively moving forward per our plan and customers are happy with our progress," Boeing says.
The company's board of directors met to consider the "authority to offer" milestone on the 777X programme on 28 April, a day before an annual meeting of shareholders.
Authority to offer is the final step before an official launch in Boeing's process for bringing a new commercial aircraft to the market, but this does not guarantee that the programme will be launched.
"The timing of a decision to launch the programme will depend on market response during the next phase of our discussions about the airplane," Boeing says.
Boeing still plans to introduce the 777X into service by the end of the decade. General Electric, which supplies the GE9X engine, is aiming for certification of the propulsion system in mid-2018, which usually pre-dates a scheduled entry into service of the completed aircraft by at least a year.
Company officials slowed the programme after the departure last year of Jim Albaugh, previously chief executive of Boeing Commercial Airplanes. Albaugh had wanted to launch the 777X programme by the end of 2012, but his successor Ray Conner wanted to take a more patient approach.
Some customers, such as Emirates chief executive Tim Clark, protested the slowdown of the 777X programme, while others including Air Lease chief executive Steven Udvar-Hazy wanted Boeing to focus instead on the 787-10X.
Boeing's board of directors approved the authority to offer milestone on the 787-10X last October, and the type is expected to be launched very soon - perhaps at the Paris air show in June.
If the 777X is launched at the same pace, Boeing could reach that step in the fourth quarter of this year. But some industry officials have recently been putting pressure on Boeing to move faster, especially in the wake of British Airways' recent selection of the Airbus A350-1000.