3 times. BA around 20 years ago from LHR to JFK from WT to Club. In 2003 with Lufthansa from Frankfurt to Bangkok again economy to Business and once flying from Mexico City to Palenque economy to business. Never to first though.
I often asked for an upgrade in the past especially when flying longhaul. The Mexican one though I didn't ask for but when I saw row two on my boarding card I knew where I would be sitting. I'm no longer flying as often as previously, mostly short haul and I'm often flying budget so no upgrades. The last couple of longhaul flights though have been in paid or redeemed business class so I'm waiting for an upgrade to first. Maybe on my trip to Namibia in the July, though I don't have any status now as I'm not flying very often so I doubt I will ever see a first class seat unless I want to pay for it.