The text on the postcard reads: "D.J. Is this how you did when you were at camp I have got that place at Inverurie so I am just staying here until I go to it I go to it on the 31 July N.S."
I assume the camp Nellie is talking about is a military camp. Jack was with the 4th Cameron Highlanders for 1 1/2 years. The 79th Regiment of Foot (Cameronian Volunteers) was raised on August 17, 1793 from members of the Clan Cameron by Sir Allan Cameron of Erracht. Originally an Irish regiment, they became part of the British Army in 1804 and in 1806 were renamed the 79th Regiment of Foot (Cameron Highlanders). In 1873, they became the 79th Regiment, The Queen's Own Cameron Highlanders (source).
In 1908, the 4th Battalion was formed, based at Inverness with the Seaforth & Cameron Brigade in the Highland Division.
So, in doing the math, that means that Jack was a member for 1 1/2 years between when it formed on (or after or about) April 1, 1908 and when he left on June 4, 1910. They had an annual camp which is likely what Nellie was referring to.
In 1916, Jack joined the Canadian Expeditionary Forces (CEF) with the B.C. Bantams - you can read all about that odd little battalion in my published article (self-promotion, self-promotion). It is on his attestation papers to the CEF that he stated his previous military service with the 4th Cameron Highlanders.
Jack would end up in France on the front lines in Lens during the battle for Hill 70. He was shot and ended up in hospital for several months before joining the Stationery & Typewriter Service (he was a trained compositor or printer). He remained in Great Britain until he came home to Canada in August, 1919.