If the curves are set to loop before and after the first frame, then the first and last frame of your cycle should still be identical. For example, if your animation is 100 frames long, with frame 0 and 100 being identical. Any curve that has identical start and end keys, is 100 frames long, and is set to loop can be…
assuming this is for a game engine. You can offset an entire animation curve in which case you should set the curve to loop pre and post infinity (beyond first and last frame). offset the curve but don't adjust the playback range. When you export keys will be baked for the playback range and keys outside will not be…