An approved template is only useful if someone answers it. The ones that work name the person, mention what they asked about, and ask for one reply.
One job per template
A welcome, a reminder and a follow-up should be three templates. Mixing an offer into an appointment reminder is how messages get ignored or rejected.
Keep the line short enough to read on a lock screen.
Leave a way to answer
End with a reply the team can act on: YES, a time, or a request to talk to a person. WapiNEXA can pick up that reply in the inbox and stop any further follow-up.