I don’t want to be a meanie, but cork’s advice is suspect. Cork has admitted to having never attended a session. Yet the OP here is specifically asking about sessions. On several occasions cork has admitted to having not played the wooden flute for very long. But he is very free with such misguided advice as this: Simply, the upper hand thumb is not used to hold the flute, at all, not on any transverse flute.
…the upper thumb is not used to hold the flute? Excuse me… Not at all? I just don’t get this. Did I misunderstand something? Is every traditional player I’ve ever known holding the flute improperly?
Here is another bit of advice that I don’t understand: …try resting the flute on the base of your upper hand index finger, just above the knuckle. Respectfully cork, absent glue, or holding my hand under the flute, I don’t see how this can be done. Perhaps a picture would help? Or a clip on youtube where we can see this position? Or would cork refuse to do this too, because, as with posting a clip, he “…actually prefer[s] for there to be some doubt about whatever flute playing advise I might have…” Cork, why would you prefer that somebody doubt your advice? Why give advice to a beginner if you think the advice is doubtful? It sounds to me as if you are hedging your bet so you won’t be held accountable for your misguided efforts to help a beginner.
I understand that this might be an important social venue for cork, as it is for many people. And I appreciate that cork’s intent is well-meaning. But this is also a “how-to” venue for many people. For some it is more than just a place to spend some idle time. Somebody with some experience can participate here and not present himself to beginners as an accomplished expert. It would be preferable if cork said “I don’t use my thumb to hold the flute,” rather than the definitive statement, “…the upper thumb is not used to hold the flute.” When beginning players come here looking for advice, cork’s “help” could in some instances not only impede their progress, but could put them off the flute forever. My counter-advice is that anybody should be very wary of any suggestion made by cork. And my advice to cork would be to back off on the need to present oneself as an expert, at least until you have shown that you are in fact an expert.
I like what you said about warming up. But in a session that isn’t always possible. That’s why many sessions start with slow jigs or hornpipes before accelerating into reels. Getting oneself set to play is very important. I appreciate your saying, “That’s what I do.” I thought that was very modest of you. But should also have mentioned your total lack of session experience - unless that has changed in recent years.
To the erstwhile Matt Molloys who have been playing for less than a couple of years: can you imagine taking advice on your golf game from somebody on the internet whose only claim to expertize is validated by what he says in a chat group? My own advice here (and not to be doubted!) would be to find a good teacher, or at least a good player whom you can observe, watch clips of good fluters on youtube, don’t squeeze the flute in a death-grip, and try to find a comfortable position – one that will reduce tension. Oh yes: and play slowly.