Leave your phone plugged into the telephone wall socket. When it stops working (presumably somewhere between Saturday and Monday) switch it over to the hub.
Aside from VM not giving out the correct dates, the switchovers don't always run to schedule anyway, as reported on here, so it is usually best to leave the phone in the wall socket until it no longer works. Then try the hub's TEL1 phone socket via the adapter, maybe along with rebooting the hub for good measure.
Some on here have also reported, in past topics, that the switchover process took a full 24 hours to complete, with the line from the hub partly working in between (outgoing but no incoming calls, for example, for a time).
