The $10K SALT (state and local tax) limit is the sum of:
State Income Tax OR State Sales Tax (whichever is higher)
+ Real Estate Tax
= at most a $10K deduction
In your case, if your state income or sales tax paid next year is at least $2K, then you will max out the SALT deduction. In order to itemize next year you'll need to have at least $2K more in deductible expenses if single (e.g. mortgage interest, charitable donations, medical expenses over 7.5% AGI) to hit the $12K deduction, or $14K more in deductible expenses if married to hit the $24K deduction. (Yes, the $10K max SALT deduction is the same for single or married, which truly is a marriage penalty.)
If you have the option of paying your property tax early (good for you if your county allows this), then it absolutely makes sense to do it if you can itemize this year and you won't be able to itemize next year. If you can itemize next year, but wouldn't be able to itemize if you pay your property tax this year, then it also makes sense to pay it early.