There is described a labeling apparatus (1) for applying labels (2) onto a succession of articles (3) and a method of setting-up of said labeling apparatus (1) prior to the application of the labels (2). The labeling apparatus (1) comprises a transfer drum (21) for retaining on its outer surface (22) labels (2), a glue application roller (19) having an outer lateral surface (20) and being configured to apply a pattern of glue onto the labels (2). The transfer drum (21) comprises a plurality of pad assemblies (24) arranged along its outer surface (22) and pad assembly alignment means (42) configured to modify orientation and/or position of each one of the plurality of pad assemblies (24) to a respective working configuration for aligning each one of the plurality of pad assemblies (24) with respect to the outer lateral surface (20) of the glue application roller (19).