How long after being introduced before something magical happens?
Traditional advice is that a performer should "grab" attention, either with a very quick effect (flash bottle) or an engaging multiphase (C+R say).
Yet increasingly, particularly in mentalism acts, there can be a very long prologue and process before anything "magical" occurs. I'm intrigued by this. Does it work?

The theatrical side of theatrical magic ought to take as long as the magic.

It is a balancing act.

See Speed in Presentation in Our Magic.

Today's casual audience has distractions of social media, video games, rude behavior. plus little experience with live magic.
Their attitude be more "figure it out" or ego challenge than appreciation of awe&wonder.
You are in competition for any commitment of focused attention and time involvement. " Entertainment addiction" may also play apart.

So, in all new effects/routines that I publish, I recommend an Overture Approach where you are prepared to Shift, Branch, Reschedule or Stop
depending on what is learned about that specific audience and setting...
The balance of story and astonishment can vary to make each presentation unique -- plus, you can vary the Level of Magic to match expectations.

Mentalism might be avoided unless you have some prior knowledge of group expectations and experience.
It is more easily accepted to start with Conjuring and Branch to Mentalism that the other way around.

Sometimes, an engaging story can tell you have to proceed. Getting group member physically involved cna be good too.

I asked the same question on our local magic club Facebook page and got some thought provoking responses (it is an exceptional group). Among them the observation that Jay Sankey, a highly engaging performer, never starts with a "trick", but always interacts and builds rapport first.

Slightly spin off funsway but I'm intrigued by your "Shift, Branch, Rescheduled, Stop" approach. I have just brought to maturity a performance piece (Linking Rings - rarely done in the UK), which benefits from quite a lengthy prologue, but under harsh, competitive conditions needs to be shorter - so a very topical challenge for me!

sent you a copy of OPS Magic.