A vintage mandolin that hasn't really been played much or broken in should be approached like a brand new instrument.
The sound will probably mellow over the years (if it isn't abused or mistreated) into a sound that is similar to a broken-in model of the same vintage.
The important breakdowns are: 1900-1910 Orville Gibson labels, "pineapple" shaped tailpiece cover 1910-1920 Fixed bridge models, the biggest production years 1921-1925 Adjustable bridges, truss rods other Loar-Hart innovations 1925-1935 Varnish finish changes to a shinier lacquer topcoat.Compare a "Broken in" Gibson from the same period (1900-1907; 1908-1920) for a fairly accurate estimate of how the instrument will eventually sound.The first and fifth numbers are the year, for example 8997653 = 8997653 or 1986 ES (Electric Spanish - hollow body with fixed pickup(s) T - Thinline D Double - 2 Pickups C Cutaway or Cherry Finish 3/4 - 3/4 side and short scale SV - Stereo and Veritone wiring option Please keep in mind that Serial numbers show approximate date of manufacture.Copyright © 1995, 1996 Dan Beimborn and Maxwell Mc Cullough This page was authored by Dan Beimborn and originally appeared on the Mandolin Pages web site, now revised as the Mandolin Archive, a vintage gibson mandolin guide.Mine sat in the shop for 2 years after the first owner died, and it took about 2 weeks of solid playing to get it to have a "wide open" sound again..
The best thing you can possibly do is try several different instruments.
The early prototype models were hand-built by Orville Gibson himself, and are very thick and chunky looking as evidenced in this photo of his workshop with many of the earliest A and F model mandolins made hanging on the wall (photo used with permission of the Gibson company).
The basic "A" and "F" model shapes were developed around the turn of the century, and have become the basis for most serious imitators since.
Instruments can take anywhere from 1-10 years to really break in, depending on how often you play.
Sometimes instruments that haven't been played in a while are "sleeping", it can take a month or so to "re-break" them.
For guitars made prior to 1977 use the extended search function.