Hi @DannyP, 

Great to see you’re considering the customer experience in regards to receiving SMS messages! This is considered best practice as customers are immediately pinged when you send them an SMS and is a more personal and immediate message than an email. I would suggest Creating a Time Delay in Your Flow as this will allow you to choose the time and day that you want customers to receive your messages. As shown below, a customer is defaulted to receive an SMS during the hour you choose in their specific time zone, you do not have to manually configure this. However it is important to note that Klaviyo cannot restrict or prevent a message from going out after a certain time period, you will need to choose the specific hour you want your message to send and on what days. 

I’d also suggest checking out this Community Post on more information on Best Practices for SMS sending in a Flow! 

Thanks for being a part of the Community! 

-Taylor 

Thanks so much @Taylor Tarpley that was so much help. I can’t believe I didn’t see the ‘recipients local timezone’ selection!