I feel like what is needed is some immediate strong feedback in the plugin that it is setup correctly (api key validated), that the requests will start showing up soon. Something that is so in your face that you cannot miss it, and positive enough that the user feels an accomplishment, that they are ~done.
However I also understand that people want to go to work and test the implementation, and if the plugin takes an unknown time to get up to speed, it creates an unnatural pause in their workflow. Could the plugin force a critical css request for the home page straight away after validation; do you think that would help mitigate this problem?
and similarly from a user (who first cancelled but re-tried and now is happy);
You should help the impatients users (like me), that do not see immediate results, to let the plug-in do its job for a couple of days... maybe add a completition bar and a funny icon and a zen motto "relax and let me do my job, perfection requires time"
and similarly from a user (who first cancelled but re-tried and now is happy);