You cannot specify a Date field as the Record title.
Fields that can be specified as the Title field

However, you can use a Calculated or Text field, which can be specified as the Record title, to display the content of a Date field as the Record title.
To do so, you need to set a formula to display the content of a Date field in a Calculated or Text field, and then specify the field as the Record title.
The detailed steps are as follows.

1. Check the field code of the Date field you want to display as the Record title.

2. Place a Calculated field, then click Settings from the gear-shaped Settings icon at the top right of the field.

3. Enter the field code of the Date field, which you have checked in Step 1, in the Formula input field.
   Select Date (Aug 06, 2012) as the display format.
   

4. Click Save.

5. Click Save form on the upper left side of the screen.

6. Specify the Calculated field as the title field.
   Setting Title field

Update the app to complete the setting process.

To display the content of a Date field in a Text field, you need to use the "DATE_FORMAT" function.

1. Check the field code of the Date field you want to display as the Record title.

2. Place a Text field, then click Settings from the gear-shaped Settings icon at the top right of the field.

3. Select Calculate automatically and enter the formula.
   For example, if the field code you have checked in Step 1 is "Date", the formula is as follows:

   DATE_FORMAT(Date,"YYYY-MM-dd","Etc/GMT")

   

4. Click Save.

5. Click Save form on the upper left side of the screen.

6. Specify the Text field as the Title field.
   Setting Title field

Update the app to complete the setting process.