The first "modern" NJ windshield stickers were issued in 1956.
When NJ adopted staggered registration renewal on April 1, 1956, all cars got 1956 tabs for their plates and a windshield sticker expiring in 1956 or 1957.

The windshield stickers for 1956 and part of 1957 were 2½ x 2½ inches.

In late 1957, the size changed to 3 x 3 inches.
Shortly after that, the year got moved to the top of the sticker, and the expiration date was printed on the bottom.

The blue - yellow - green color cycle was used from 1970 to 1983 (and again from 1986 to 1997).

Starting in 1977 some stickers used separate month number "inserts", and some had the month number printed as part of the sticker.

In August of 1982, NJ ran a pilot program with biannual inspections; the first 1984 inspection stickers were actually issued in August of 1982.
This practice was ended by December, 1982.
(The latest month that you will see on a 1983 inspection sticker is September.)
Info from Steve Bier

Starting with the 1984 windshield stickers, the placement changed to the driver's side of the windshield.

Also for 1984 and 1985, the windshield stickers had the months of expiration around the edge, and the proper month was punched out.

These were too hard to read (I guess we were used to the big month number) so in 1986, the stickers reverted back to the "standard" type.