Good news, this is now live in Breww 
Hi Phil, this should hopefully let you drop those calling spreadsheets! Customer lists can now run as workflows: pick a list (Connor’s filter above works well as a dynamic list), choose how often it’s worked through, and Breww opens a fresh checklist of those customers each period, with a task for the people assigned to it. Each row flags customers who are overdue, at risk of churning or due to order in the next 7 days, based on Breww’s order predictions, and your team can mark each customer as completed, log the call and create orders without leaving the page.
You can also now record the days and times each customer prefers to be contacted. Workflows list customers in the order their windows open, which covers the “sort by a call time” part of your question, and “Only contactable now” shows who you can ring right now.
Full details are in the announcement: Customer list workflows and preferred contact times: work through your customers regularly, at the right time for each
I hope this helps!