From this it appears that John was with the 2nd Battalion throughout his service. That would mean that he returned to Ireland in 1902. In 1903 the 2nd bn were in Kinsale, then went to Gibraltar in 1904, then back to Limerick in 1907, followed by Tidworth 1909 and Aldershot 1913. From the information we have it's not possible to know if he remained with the colours throughout the period up to the First World War, or if he went into the Reserve for a period of time. Have you located him in the 1911 census?