This is the way.
Decide where you want the downlights, leaving room where joists are.
Mark on the nearest joist where the light will roughly go.
Clip the cables to the joists, keep cables close to the mark. Where you have two ends of cable, just tape them together.
Try to arrange the cable ends so they are loosely in the void, rather than hanging down.
Do NOT ask the plasterer to pull these wires through the plasterboard. Let him board straight over.
If there's any cables you do want pulling through, for example a smoke detector cable, clip it to very bottom edge of the joist, and even write on the bottom of the joist in marker pen, 'pull thru'.
Draw a plan of where the lights are, with all measurements.
Keep this plan under your pillow every night till you need it again.
When ceiling is filled or skimmed, but before the final coats of paint, mark out the lights. Use a chalkline to ensure they are in straight lines.
Drill holes, fish cables out. The cables taped together will make pulling them out easier, as when you pull one cable, the other cable comes with it.
Do NOT get the plasterer to pull these spotlight cables through the plasterboard. He will NOT make the holes in the right places.
