Hook for theme activation

“switch_theme” might be the hook you’re looking for: https://codex.www.ads-software.com/Plugin_API/Action_Reference#Template_Actions

However that’s not the easiest way to do it. Just add some add_option( 'name', 'value' ); ‘s to your theme’s functions.php file and they’ll be set (if the options don’t exist) as soon as your theme is used.

Further reading: https://codex.www.ads-software.com/Function_Reference/add_option

Thanks for the awesome suggestion, Viper. ??