As your animation gets closer to being perfected, you might find the need to slightly offset the timing of one or more objects relative to the rest.  Spriter actually keeps separate time-lines and key frame per object.  To view and edit them you need to expand the time-line area upward by left clicking the top of the time-line window upward.  Now you can left click and drag to change the time position of any objects key-frames.  You can also delete them via the delete key after selecting them.
Advanced Time-line Editing

Spriter Pro User’s Manual version 1.4