check_after_sign_in.js

// app/assets/javascripts/check_after_sign_in.js


$(function(){
  if (Cookies.get("run_hubspot_stuff")){
    // run the HS stuff
    
    // clear out the cookie
    Cookies.remove("run_hubspot_stuff");
  }
});

set_after_sign_in.rb

# config/initializers/set_after_sign_in.rb


# Run code after Devise sign in 
# http://stackoverflow.com/a/27337802/126636

Warden::Manager.after_set_user except: :fetch do |user, auth, opts|
  cookies["run_hubspot_stuff"] = true
end