It looks like you are using TurboTax Business, so assuming you a filing for a Multi-Member LLC, as you go through the "About Your Business" section of the program, you will indicate the date you started your business. This date will appear on line E. of page 1 of Form 1065. Also in the "About Your Business" section, you will see "Are You Using a Calendar Tax Year?", which after you input the started date will indicate that you are using a "Short Year" (see screen shot below).
If instead of a mulit-member LLC you are a single member LLC you are a disregarded entity for tax purposes (unless you've requested S-Corp status) and you file on Schedule C, as part of your personal tax return. You would check a box on Schedule C that you started your business in 2018.
It looks like you are using TurboTax Business, so assuming you a filing for a Multi-Member LLC, as you go through the "About Your Business" section of the program, you will indicate the date you started your business. This date will appear on line E. of page 1 of Form 1065. Also in the "About Your Business" section, you will see "Are You Using a Calendar Tax Year?", which after you input the started date will indicate that you are using a "Short Year" (see screen shot below).
If instead of a mulit-member LLC you are a single member LLC you are a disregarded entity for tax purposes (unless you've requested S-Corp status) and you file on Schedule C, as part of your personal tax return. You would check a box on Schedule C that you started your business in 2018.