You are about to perform a sleight that is not invisible--say a top change or a pass.

You tell a joke. The audience responds.

Do you perform the sleight

a. as you say the punchline
b. as the audience responds
c. after the audience responds
d. none of the above
e. I'm framing the question incorrectly

Kinda going with E, but it may be pedantic.

It's difficult to give a hard and fast answer because it will change with each audience.

You do it when they are distracted and when a natural motion covers the move.

In the situation as given, I would probably do the move while making a gesture to emphasize the punchline, while they were laughing at it.

I perform the Top Change using a Slydini principle - "Shoot Then "Rest.

The card to be changed is in my right hand - the selected card is on top of the deck in my left hand.

I raise both hands showing the wrong card and say "Ta da"

The I rest dropping both hands and make the Top Change.

Then I move my right hand away with the changed card and say something.

Landmark, it does depend. The typical response is to ask the spectator a question and do the move when they look at your face. That isn't always going to be practical. I do think Gerald's example of "shoot then rest" makes sense. Doing the move in the "rest" phase should hopefully result in less scrutiny. In general, when I see these kinds of questions, I wonder whether you somehow are inviting the spectators to look at your hands. I hope that is not the case.

One way that magicians unwittingly invite scrutiny is when they themselves look at their hands. The audience tends to look where you look and believe me they will most certainly look at your hands when you do.

I did an experiment once. I was teaching a group of young magicians and the trick that I used to demonstrate misdirection was 'The Professor's Nightmare'. I showed them how I did "the dirty work" with my left hand as I looked and reached down to grab the bottom of the longest rope. I made a big deal out of cocking my head, bending at the waist and reaching. They couldn't not look. Even when they tried, after I told them what was happening, they had to fight to not look down. So misdirection works. Or better yet, direction. I created a desire to look down, so I directed their attention.

Another thing that I've noticed on difficult sleights is the performer tenses up. There is almost a tendency to "look guilty". If that's the case, relax. When you relax, they tend to also.

I think any of the above...
Many could make the mistake of practising their approach to doing a move alongside patter in a very rigid way.

When it may be helpful to adapt your timing to the live situation .i.e. wait for the offbeat to happen.

So I guess if looking at some of what has been written already, it would be about willing to wait for the rest?

I wouldn't be afraid to wait,and keep waiting for that sweet moment to do the top change for example. There's no need to rush. Beef up your presentation, develop your patter, slow down.
As time passed, heat cools off.
You will feel and seem like a much more natural and confident performer too.

So any of your options may apply,as they in that particular case may be the fitting time.

I would go with d) although the rest is not necessarily wrong. When you tell a joke for example and people laugh, you should, according to Tommy Wonder, execute the move as late in the laugh as possible. If you do your move to early, the audience might be interrupted in their laugh catching your move. So you have to wait, until the laugh is almost! over.

As it is for me, I create the Offbeats not by lines or jokes, but by integrating the "moves" into my natural way of behavior and by moving my hands naturally while talking, making gestions towards a spectator and so on. Also, I have absolutely no attention to the secret move I have to do. My attention is to the move or the natural behavior I want the spectators to see.

Play with various ways, see what works best.

I agree with others when they say that it may well be different vin different situations, and so each instance should be assessed, so as not to blindly do the same each time.

I also agree that not all offbeat is created by patter or jokes.

But in the example you give, I'm inclined to go with 'when the audience responds'.

Funny moments are about tension and release, and so the release comes when they respond i.e. laugh. It is in this moment that they are no longer focused on what they were focused on before.

The idea of tension and release is good to think about for offbeat moments in general.
As an offbeat can be in-between phases, or after a moment of magic too. Again, another 'release'

Description From Youtube:
This audio clip was recorded at Tony Slydini's Studio of Magic in NYC on January 16, 1974. Tony is instructing me on the basic "tense" and "relax" positions in his philosophy on timing and misdirection techniques.

The key to Slydini's whole timing techniques is having a slight hesitation after the "tense" (shoot) position. That gives a natural drop of the hands to the table, otherwise the drop of the hands happens too fast. This is why Tony's magic is so deceptive; everything looks natural and as it should look to the spectator. You will hear him discuss how I, at first, bring the hands up too high. At the end, Tony says the following about my learning: “You must have saw already something about my magic. You went the right way some they do, they don't do at all, they try to do but then nothing.” I was so proud to hear him say that when I reviewed the footage.

This clip represents just 1.5minutes of footage of over 38 hours of audio lessons that Slydini allowed me to take during my time spent studying with him. Please "like" and "share" this, and subscribe to my Youtube channel if you want me to share more of these priceless clips publicly on Youtube for all to enjoy.

In addition, you might want to check out the Bill Wisch "Timing Techniques System", available at https://www.billwisch.com/store My father created an entire system of instruction utilizing the "beat" and the "off-beat". He showed this system to Tony, and Tony loved it. It has been lauded by many in the magic community as the quickest, simplest and most practical method ever devised for learning sleight-of-hand

Audio Clip Copyright Bill Wisch and Wisch-Craft Productions 2020

Hi landmark,

Check out David Regal's non-obvious approach in executing the sleight under ephemeral concealment in these two trailers.

That's very clever. I've seen Regal do that a lot, but I always assumed something else was going on. No wonder I couldn't duplicate it. That's really clever.