If you have income from gambling in 2019, you will wait to report it on your 2019 return, however, you may be required to make 2019 estimated payments.
IRS Tax Topic 419 (https://www.irs.gov/taxtopics/tc419), states "A payer is required to issue you a Form W-2G.pdf, Certain Gambling Winnings, if you receive certain gambling winnings or have any gambling winnings subject to federal income tax withholding. You must report all gambling winnings as "Other Income" on Form 1040, Schedule 1.pdf and attach this to Form 1040.pdf, including winnings that aren't reported on a Form W-2G.pdf. When you have gambling winnings, you may be required to pay an estimated tax on that additional income. For information on withholding on gambling winnings, refer to Publication 505, Tax Withholding and Estimated Tax"