Read, 31, who confirmed on Wednesday he had signed a contract extension with New Zealand Rugby until after the 2019 Rugby World Cup in Japan, said he would get the thumb out of the protective cast on June 10 and then have another X-ray.
"It's a bone break so you've got to let it heal," Read told reporters at his former secondary school Rosehill College in south Auckland. "The fact is you don't really know how it's responding.
"We'll X-ray it again and then it's a return to play process. That gives me two weeks before the (first) Lions test which should be plenty of time."
The All Blacks host Samoa at Eden Park on June 16 to help prepare for the Lions series but Read, who had said earlier it was unlikely he would be able to play that game, repeated it might be too early for him.
"One week. We'll just have to wait and see how the thumb reacts," added the number eight as to whether he might be available for the Samoa game.
The decision by the Canterbury Crusaders loose forward, who has won 97 caps since his debut against Scotland in 2008, to remain in New Zealand until after the Japan World Cup was a boost for coach Steve Hansen's planning.
He joins 15 other All Blacks committed until after the first World Cup to be held in Asia and Read said being elevated to the captaincy after Richie McCaw retired following the last global tournament had been a factor in his decision.
"Five or six years ago I might have looked overseas potentially after 2015, but circumstances now and being skipper, there's a lot of work to be done with this All Blacks team and some awesome challenges ahead," Read said.
"It's good coin. I'm more than happy with what's coming my way. The whole package is nice for the family and it's great to be here in New Zealand."
(Reporting by Greg Stutchbury; Editing by John O'Brien)
