My memory is vague as to the timeline. But colliers was used as far as I can remember in the 60's and early 70s slowly dying out . Tykes was apparantly the nickname since inception. But in my view. Not the predominant one it has been over the last 50yrs or so. Interesting article here. https://whatsbehindthebadge.com/index.php/barnsley/ I see Tarn becoming more of a nickname in the near future.
Through the 60's and 70's Littlewoods Pools produced a booklet at the start of each season that gave a rundown of all 92 clubs in the four divisions, they always quoted The Colliers as our nickname.
I agree about Tarn. I recall seeing Colliers written as a nickname in publications many years ago but never once have I heard it spoken by Barnsley fans. Going to watch Tykes was heard the odd time but mainly going to watch Reds or Tarn was the most common in my time. So I reckon if it ever was a nickname it died out in the 40's. Think Tarn is more prevalent today.
The main issue I think would be the fact I believe Chesterfield fans used the word Tarn long before we did. My workmate from Chesterfield, a liverpool fan, if going to watch his local club would always say going to watch Tarn. Not as though other clubs don't share nicknames mind. Eg Magpies Robin's Iron
Well I do like it because it's our heritage and I'm not from a direct mining family but it's in my blood.