General aviation pilot reported they taxied past hold runway short lines with an aircraft on short final approach; resulting in a critical ground conflict event.

Narrative

While doing preflight runup I was monitoring busy Unicom with most transmissions from a nearby airport (ZZZ1). However; I heard some ZZZ but the location was indistinct for an unknown reason. I think that I heard three ZZZ transmissions but I guess I got too complacent to register that THIRD TRANSMISSION FROM AN AIRCRAFT OFTEN IS 'ON FINAL'. I cannot believe that I was so incompetent. Many of my somewhat recent flights were from my busy controlled home airport (ZZZ2) to uncontrolled airports.I then made a transmission 'ZZZ traffic; Aircraft X taking Runway XX for departure to the east.'I then looked towards the approach direction (I'm real darn sure) but didn't see anyone.I then taxied past the hold short line but just shy of the runway edges I saw a plane on VERY short approach. I slammed on my brakes and stopped short of the runway edge and he executed a go around but veered towards me rather than away from me. It was very close! WOW!I'm ashamed of my incompetence that would have mostly caused a possibly fatal accident.I got complacent. There was no excuse for my failing to determine where the other plane was before starting to take the runway. Always in the past I'd transmit 'Other aircraft at airport; where are you'. I guess that almost was written on my gravestone.I then transmitted an apology and that his position reports were garbled.Factors certainly start with my flying only about 21 hours in the past year; some due to two [expletive] former flight instructors who wouldn't sign off my biannual flight reviews unless I was up to Aerobatic Team standards in clear violation of standards. After firing the first one who demanded when he 'failed' my quadruple redundant electronic navigation that I navigate through the swamp by a canal when I simply could have flown east to the coast and recognize the nearest airport as each one has a different configuration. The second one held me to Commercial Pilot standards for precision landings rather than Private Pilot standards.Still; I have no excuse and will NOT make this mistake again. I absolutely will fly more. Currency is the key.