You need to add a column to Admin / Database / Users / Properties with the following info:
Column Name: Add_Date
Column Type: DATE
Not Null: Yes
Default: 0000-00-00
Form Display: Add Date
Form Type: HIDDEN
Then add the following to signup_form.html
Column Name: Add_Date
Column Type: DATE
Not Null: Yes
Default: 0000-00-00
Form Display: Add Date
Form Type: HIDDEN
Then add the following to signup_form.html
Code:
<input type=hidden name="Add_Date" value="<%GT::Date::date_get()%>">