Need to add one-time "SKIP INTRO" page containing subscriber form

Can you point me in the right direction?

When visitors go to my WP homepage I want to greet them with a "SKIP INTRO" splash page that will only display an optional email signup form (it would be a Gravity Form). I would like visitors to be able to either fill out the form, submit it, and then continue on to the standard homepage -OR- they can choose to not fill out the form and instead click on a "SKIP INTRO" link that would be below the form.

I found some JSFIDDLE code snippet that does much of this already:

(Note that in the JSFIDDLE example I would replace the "kitten photo" with my Gravity Form. I also would like to add code to the JQUERY so that it only shows the form once per session.)

Unfortunately the JSFIDDLE example is for a non-WP page. Could you provide some guidance as to how to properly integrate the example's JQUERY code into my WP child theme?

(I am uncertain about whether it has to be enqueued or whether it needs to be in an external .js file)

Any pointers/guidance much appreciated as I have a deadline for this task. Thank you