Seeing Hubert Laws perform in the mid to late 1970s was probably my first recollection of a flute being played through some kind of amplification. I can't recall if he was using a headset then, or playing into a stand mic. Another flutist around that time, Tim Weisberg, used a Barcus Berry mic that replaced the headjoint cork and so I remember buying one of those. Unfortunately, I hated all the key noise it captured and wound up not using it.
For a few years, I dabbled in my own headset microphone setups, using different brands of lavalier mics attached to a telephone operator's headset that positioned the mic near the flute embouchure hole. This then plugged into a Mesa Boogie Mark 1 guitar amp. That arrangement worked well for low to medium volume level gigs (loved the spring reverb on the Mark 1!), but as soon as the volume level of the band got loud, I would have feedback problems. Then one day (circa 1987), I went to go see Dave Valentin play at Kimball's in San Francisco.
Dave sounded fantastic just playing through the house PA. So I asked him at the end of the gig why he didn't play with a headset, and he said it was because he couldn't back off the mic. That was enough of a reason for me. Shortly afterwards I went and bought a Shure SM-58, a Boss digital delay pedal and a PA system (and sold my Muramatsu flute and the Mesa Boogie to pay for it!). Been playing through a SM-58 either into PA (or guitar amp) ever since.