From the National Association of Realtors, State and Local tax deductions: 

As most of you know, the new Tax Bill will be in effect beginning January 1, 2018. Please see below for information pertinent to real property tax payments.

• The final bill allows an itemized deduction of up to $10,000 for the total of state and local property taxes and income or sales taxes. This $10,000 limit applies for both single and married filers and is not indexed for inflation.
• The final bill also specifically precludes the deduction of 2018 state and local income taxes prepaid in 2017.

NAR has produced a comprehensive document that summarizes the changes affecting real estate professionals and homeowners.  All individual provisions are generally effective after December 31, 2017 for the 2018 tax filing year and expire on December 31, 2025 unless otherwise noted. The provisions do not affect tax filings for 2017 unless noted.

https://www.nar.realtor/taxes/tax-reform/the-tax-cuts-and-jobs-act-what-it-means-for-homeowners-and-real-estate-professionals

We strongly recommend you consult your CPA with regards to whether pre- paying your 2018 real property taxes before the end of the year is in your best interest. Should you decide that it is we have been told that property owners can pay their expected 2018 taxes online on or before December 29th. We understand this applies for owners who hold their property as individuals, versus corporations, however we again recommend confirming this with your CPA.