Hello Paresh

Do you want to create a Form name based on some Fields value in your Form or
you want a GUID Kind of thing which is unique for every form

Suggestion:

I usually add a hidden text field to the form data structure called formName
and in this field I specify the name of the form as the defaut value.  When I
am setting up my submit rules where it says the filename for the form then I
pick "function" then "concat" and I do something like:

formName  employeeName  reviewDate

[asuming there is an employee name and review date field in the form]
So when it gets submitted the filename is:

ReviewJohnSmithdate

BonusTip:

when you put the value in the formName hidden field use an underscore
character on the end so your final filename in the library will be like this:

Review_JohnSmithDate.