The mayor has introduced more than 20 local investors who have pledged at least $1 million each to be minority owners in the team, but he has yet to announce the major equity partners.
Stern said he has no meetings scheduled this weekend with Johnson, who plans to be in Houston, but said the former NBA All-Star may even meet with the board before April.
Until then, the Seattle group will have to wait.
"We have a process that we've been doing for the last some-odd years, probably 50, where we take applications, we do all the work and the work has begun," Stern said. "And so the April 18th board meeting is what we're aiming for for final resolution on this issue."
Stern spoke after joining former NBA star Bob Lanier, a special assistant to the commissioner, to announce a four-year contract extension between the league and the Retired Players Association, commemorating their 20-year partnership.