As noted a couple weeks ago, there are two new Subways in the works in the neighborhood: one is headed for the landmarked space that was last home to Leaf & Bean, and another is coming to 525 Fifth Avenue, between 13th and 14th Streets, in the storefront last occupied by a jewelry store.
The latter got some temporary signage last week, and permits have been issued to renovate the space, build out a new storefront, and for the "installation of a business awning wording 'SUBWAY'." Construction hasn't officially begun yet, but once it does I imagine that the process has become so streamlined that it'll take no time at all to complete.
UPDATE: Looks like construction is already well underway. See what I mean?