Message groups of clients based on appointment date

It would be SO helpful if we were able to message a group of clients based on when they are booked in.

For example, when the latest lockdown hit the UK, rather than having to SMS every client on our account (which is far too expensive and pointless) a filter that allows us to select clients based on booking dates so we could just SMS each client in January or the next 6 weeks, etc, would make much more sense.

In fact a more in depth filter on client selection would be ideal.