Global form fill put measurement

Hi all, initially we planned to have a welcome program, therefore everyone completing the form would receive an email and we could track globally the number of people completing form and entering our database.

Now instead of sending a welcome email, as soon as they complete the form they will be added to the specific nuture programs. 

I was wondering the most sensible way  /program vs smart list vs smart campaign, how i measure everyone completing the form prior to them all going into their designated nurture programs.

any advice on how to handle this would be appreciated?

thanks