I would make a marker at the offset position (1:10 to the right of the first key), then go into spline editor, select all keyframes (Ctrl A) and then drag the first one to the offset marker.
Or copy all keys, delete them, then go to the marker and paste them.
Incidentally, if you drag a project onto an empty timeline and position it wherever you want, offset wise, it behaves as a subproject. Then you can expand it, and all of its relevent timecode references are now altered to the new timeline position. That means inpoints, outpoints, markers, keyframes, everything.