I frequently follow up on Sundays....Everyones religion is different...I certainly learned that when a large portion of my wifes family refused to attend our Saturday afternoon wedding (nor send a gift :( ).
Matter of fact earlier today I was with my kids at my parents house but pulled out my cell and called a client I need to delivery a policy to. I was driving right by her work tomorrow for other business and I was going to at least try and reach her to deliver the policy. I reached her on the phone and set up a 5 minute policy delivery for Monday.
The bigger issue for me on Sundays has not been to be chewed out based on religion but instead based on a football game. I do not call until the afternoon when most people have finished worship and I always call my Monday appointments Sunday to confirm. I live in a state where driving an 1 hour one way is not uncommon and I want to know as early as possible if the client needs to reschedule.
If you want to know as early as possible wouldn't the Friday before work better? Ask them to let you know if for any reason they wouldn't be able to make the appt.