I see the May 7th for him to go to immigration office as formality in giving him the extension of stay. That is why I said that technically he is 4 days overstay now.
You won’t be fined but I am not sure if not going there last May 7th will affect your application/under consideration. In the past, I have missed 1 day getting the extension and it was alright. Not sure about missing it for 1 week.
The white slip is for 90-day reporting and it is not your extension of stay. You should have gone to the immigration last May 7th to collect the extension of stay. You can still go there today and collect.