I always submit my report on the 1st available day, like 2 weeks before the due date. I then have plenty of time to chase it up if I don't hear back from them. My wait has been as long as 4 days and as short as 5 hours, but they've never let me down.
I do wonder whether our office in Sakon Nakhon does a batch of report checks maybe once or twice a week resulting in the spread of results.
Some people, in the past have quibbled about doing the report early saying they loose out on a number of days. Wow, it takes 5 minutes. What's the issue?