Typically Amazon is supposed to update them by 9am PST. However, they have been all over the clock, with many reports posting much earlier and some much later. I have many more details about Amazon Associates reports on my site. You can also see the dates/times when Amazon Associates posted reports over the previous 30 days. This list is updated daily. Lastly, if you wish, I have a service which will automatically send you an email the moment Amazon posts their daily report. This way you don't need to keep going back to Amazon and checking. It's a great service and it's free. Same site as above.