Gambling winnings are entered in as Less Common Income. You may receive a Form W2-G depending on the type of winning and the amount. If you will be receiving a Form W2-G, then you need to wait and file when you have it.
Please view the TurboTax link below to determine if you will be receiving one.
Otherwise, please follow the directions below to enter in your gambling income.
Select Federal Taxes>Wages & Income>Less Common Income
Note: You may have to scroll or expand the list to view all income items.