There’s nothing to stop developer Kevin Maloney from starting sales at 111 W. 57th St., the latest sky-high condo tower rising on midtown Manhattan’s Billionaires’ Row. He has the necessary legal approvals, and an office ready to welcome would-be buyers.

But with luxury-home demand slowing and new condos piling up on the market, he’s waiting about a year before trying to sell units at the project, where the price for a penthouse will approach $60 million.

“If the market were red-hot, people would be buying off plans, throwing checks down, and it’d be great,” said Maloney, principal and founder of Property Markets Group, the skyscraper’s co-developer. “But if you have a market where you think marketing would be ineffective for now, why would you launch and spend the money? Wait.”

Times have changed from just a few years ago, when global investors clamoring to own a piece of New York’s glitziest towers signed condo contracts while the buildings existed only on paper or as a tabletop model in a sales office. Now, some developers are betting that the best sales strategy is to hold off until the projects are closer to completion, rather than releasing their unbuilt units into today’s crowded market.

This year, 5,126 newly built apartments will be offered for sale in Manhattan, the most since 2007, according to Corcoran Sunshine Marketing Group. Of those listings, 63 percent are priced in the “luxury” range, defined by the brokerage as $2,400 a square foot or more.

Foreign Buyers

At the same time, sales of New York’s most expensive homes are stalling as foreign buyers are held back by the stronger U.S. dollar, lower oil prices and economic slowdowns in emerging markets such as China and Brazil. In the first two months of the year, contracts for apartments priced at $4 million or more declined 30 percent from the same period in 2015, to 150 deals, according to a report by Olshan Realty Inc.

Weakening demand for high-end Manhattan homes has prompted some builders to delay construction, reduce prices or, in the case of a Property Markets Group project in SoHo, carve upplanned apartments to make them appeal to a broader group of buyers.

“Developers are very lucky when they hit great timing -- and this might not be the time,” said Donna Olshan, president of the brokerage bearing her name and author of a weekly luxury- market report. “Particularly in the Midtown corridor, which is the most worrisome area in New York because you have a lot of luxury product coming out at the same time.”

On Billionaires’ Row, the area fringing Central Park that’s the epicenter of the luxury boom, Maloney plans to delay marketing at 111 W. 57th St. until the 1,427-foot (435-meter) tower reaches at least 800 feet. The project, co-developed with JDS Development Group and expected to be completed in 2018, is now just past its first story.