You can apply the Schedule Form Activity form setting to open and close your form at a specific date and time.
To schedule form activity:
TIP! With form closed options, you can create a customized message or redirect to a website when your form is closed.
The Schedule Form Activity setting refers to the time zone setting in your account. Click Account in the upper-right corner and select My Account to view your time zone. The Account Creator or an Admin can change the time zone for any user on the User Management page.