Does anyone have any idea how far in advance of planting veg should chicken manure be applied to the intended planting area, e.g. runner beans and courgettes?
I'm just assuming that you are referring to the processed, pelleted form, available in plastic tubs or bags from garden centers.
as it is considered safe to handle, and is intended as a slow release fertilizer and recommended to be applied at 4 - 6 weekly intervals around established plants, I would guess it would be ok to apply it 4-6 weeks before planting / sowing.
But I would recommended that the intended planting area is well cultivated and free of weeds first.
Don't use raw chicken manure - it needs to rot and mature. Even then avoid cheap from local chickens - my mum bought that and for everafter she had chickweed growing, none beforehand.