I simply unscrew the turnbuckle from the stay and move the stay back along the first port side shroud, using a fitting (tie rod end) that I got at a hardware store to screw the stay into. There are some expensive gadgets available for bringing a babystay back to the mast and securing it ( Home - C.S. Johnson
), but my improvised method is very cheap.
On my IslandPacket cutter rig I nominally use 18 knot winds or higher as the threshold for going to staysail and reefed main.