Typically, about 60 days elapse between the time the seller accepts your offer and the time you actually close on the apartment.
The closing will be attended by attorneys for you and the seller, a title company representative, a managing agent if it’s a co-op and probably the brokers for both sides, who have no official function but come to network and pick up their commission checks. While buyers and sellers are usually there, they can elect to skip it and hand power of attorney to their lawyer.
Arrive with your ID and your checkbook, to cover any minor last-minute ‘adjustments’ that spring up. You may also need to provide proof of apartment insurance.
Ideally, your closing will last one to two hours, though any number of things like problems with the walk-through, tardy transfers of loan funds, and tardy arrivals of humans can slow things to a crawl.
Eventually, you will walk out with a signed purchase agreement, keys and a great new place to rest your head at night.