I may be wrong but I think that 50 shot FT courses started around 2000 ish.
Remember my first ever 50 shot FT course (not a GP) shot in 1997 at Nomads FTC just outside Petersfield Hampshire. Did not drive there as someone else did. Was relaxed and just enjoyed the day. Hit a 47 and was happy until I found out the next score down was a 44 when happy changed to a really happy shooters.
Was off to do a GP the following weekend when everything crashed and burned, hit a total of 17/40 with 16 splits and only 1 went down. Wind was one of those gentle move it slightly types. I do have a diary of all the FT shoots I shot until 1999, brings back memories when reading it.