Hello @SallyM003 ,
The best time to send out an email and yield higher open rates is entirely dependent on your audiences past engagement history; different industries have different days of the week and different times of the day that works best for their audience. What I would suggest is look back at the past campaigns that have been sent out and when focusing on the higher open rates compare all of those send times to each other and see if there is any consistency with them. If most of those campaigns were sent out on Fridays it would be ideal to send out then based on the engagement that has been seen already with them. I have attached a knowledge based article here that goes over this process in more detail.