In New Jersey, it is not mandatory, but it is highly recommended to hire an attorney for the closing of real estate. An attorney will be able to advise you on what is in your best interests while negotiating the more formal terms of the contract. An offer which has been accepted by the seller becomes a legally binding contract.
Attorney review in the state of New Jersey is counted as three business days (no holidays or weekends) from the date of a fully signed contract by buyer and seller, but can be (an quite often is) extended, shortened or waived upon written agreement of all parties involved.
During the attorney review period, either party can cancel the contract and any deposit money is returned to the buyer. Once attorney review is completed, you have a binding contract to purchase the home.
Additionally, typically 10 business days after a contract is signed by both buyer and seller, the balance of the initial deposit (if any) is due.
I can provide you with a list of recommended Real Estate Attorneys.