First off, welcome to the GAF.
Generally speaking, since the sword was a regulation item, in that it's design was specified in the uniform regulations, officers would be encouraged to replace their older swords with the newer patterns as soon as they could. You can see this when other uniform changes were instituted - officers made the transition to the new pattern fairly quickly. Only the enlisted men were allowed to wear older issue clothing and equipment.
In the Marines for example, they changed from the Mamaluke pattern to the 1850 Infantry sword in 1859. Civil War era photos show the 1850 pattern being worn, suggesting serving officers replaced their old patterns fairly quickly.
There were exceptions of course: Presentation swords, regardless of pattern, could be worn. Older patterns might be worn when not in formation with troops or when on campaign (should the officer want to carry a sword on campaign), and if the regimental commander allowed it. Obviously, the further away from the headquarters the greater possibility of getting away with a non-regulation item on duty (as opposed to being on campaign when almost anything went).
US Scout
Brig Gen, GAF