It rode my B17 about 10miles/day in 2 commuter sessions. After about 2 weeks, I had definate sit-bone depressions. Up till then you feel a bit slidey-about sitting on top. After a couple more weeks, the saddle was fully compliant with my own shape.

I wouldnt recomend any long hard rides on a new saddle. Go easy on the miles, and on any treatments to the leather.