I don't understand the question. Googling the phrase brings no results.
'mini' might refer to a small (3/4 size or 1/2 size guitar)
'mini concert' might refer to a short performance.
What period? Do you mean musical period? Music written for classical guitar falls almost exclusively in the romantic and modern periods, but the standard repertoire includes pieces written during the baroque and classical periods that were originally done on guitar like instruments (like Bach's lute suites or Vivaldi's guitar concerti) or that lend themselves well to the guitar (like some cello pieces)
How many songs in a concert is usually left up to the performer. If you're charging admission, it's got to be long enough that people don't feel cheated, but that could be one or two long pieces or a bunch of short ones.
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