How do you know when a sale is "In Contract"?

The listing broker is obligated by REBNY rules to update the listing's status within 24 hours in RLS (REBNY Listing Service), which is the equivalent to the NYC MLS (http://www.hauseit.com/nyc-multiple-listing-service/).

It's "in-contract" only when both the buyer and seller have fully executed the purchase and sale contract (http://www.hauseit.com/nyc-fsbo-closing-process-home-sellers/). This is after an offer has been accepted.

Yes but many sales agents will hold off updating to "in contract" so as to keep the buyer inquiries coming since this provides new leads on the buyers still out there. Who knows could lead to a new client? Hey why not make up some excuses and hold off on the "in contract" update.

followup.... most buyers will not inquire into the listing if they see "in contract"

Streeteasy will usually have a feed from the brokerage website, or it will crawl the site to ensure it gets updates as the broker makes them. So when a listing is put as "in contract" on the broker site, it will get updated within a few hours on Streeteasy. However, it is up to the broker to do this, and even though REBNY requires it, they don't enforce it. This is not to be confused with an "accepted offer". Many times a buyer will enquire about a property and find out there are "contracts out" or an "accepted offer". Some brokers will continue to show during this period, but others will stop showing at this time if they are reasonably confident the contract will get signed. At RealDirect (www.realdirect.com) we advise that showings continue for backup until the contract is signed, since at any time up to that point, either party can back out without any consequences.