Good news, this is now live in Breww 
Hi Robert, you can now record a preferred contact time against each customer and lead: the days of the week they like to be contacted and a from/until time window, together or on their own. It’s separate from delivery windows, so it can reflect when their phone is likely to be answered rather than when deliveries can arrive. Breww shows the window wherever your team is about to get in touch, and flags whether the customer is contactable right now.
For sorting, customer list workflows (also new) list customers in the order their windows open, and “Only contactable now” narrows the list to the customers you can reach right now. You can also import contact times for your existing customers from a spreadsheet.
Full details are in the announcement: Customer list workflows and preferred contact times: work through your customers regularly, at the right time for each
Thanks for requesting this, and we hope this helps!