As far as I can tell, SIC coating appears on the AIS 24/2.8 from serial no 84xxxx upwards. On this lens the difference between NIC and SIC not very obvious, and most of my information comes from comparing pictures on ebay listings where the quality and color balance of the images is hardly consistent, so it's been harder to determine the transition compared to some other lenses.
It would be interesting to compare a NIC vs SIC coated lens to see what the difference really is. Nikon brochures state that SIC is more effective over a wider range of the spectrum but I suspect the difference in practice will be minor since the older coatings were already very good.