Currently, you cannot request a reading. If you're interested in why this is, this article should help you.
However, we do offer the ability to customize your test times provided you're on the Premium plan! This will help you bring the times into a better area where your daily schedule is concerned.
If you're already on the Premium plan, you can navigate to your Sutro app, open the settings and select 'Timing.' You'll be able to adjust your testing times on this screen, and control when the TA reading is taken as well.