Seattle city planners on Thursday approved a 27-story apartment tower on First Hill. But a spokesman says the developer, Swedish pension fund Alecta, hasn’t yet decided whether to start building soon or wait.

The 328-unit project would be built at Terry Avenue and Jefferson Street.

Longtime Seattle developer William Justen, who is overseeing the project for Alecta, said the company probably will make a construction decision in the next couple months.

Seattle is in the middle of its biggest apartment-construction boom in more than two decades, and some warn the market is getting overbuilt.

Unlimited Digital Access. $1 for 4 weeks.

“Is there still time to get in on this cycle?” Justen said. With construction of the tower expected to take 2-1/2 to three years, “it takes a crystal ball,” he added.