gs provides convenience functions for working with Google Storage.
Assuming there are date objects with names like dateobject_20060102.txt
# Get the names of the latest three objects
dt := time.Now().AddDate(0,0,-3)
objs, err := gs.ObjectsSince(bkt, prefix, `dateobject_(\d{8}).txt`, dt)
if err != nil {
log.Fatal(err)
}