I am sure that steel points were probably used as soon as they became available. I have seen several arrow points cut from brass trade kettles that were dug up during archaeological digs at historic Cherokee townsites when Tellico lake was being built. The copper salts in the brass have preserved a couple inches of the foreward ends of the arrows on some of these, and they were sinewed directly into cane shafts. This confims the writing of Henry Timberlake, who lived with the Cherokee for awhile in the mid-1700s, and described their arrow making process at the time as he observed it. He mentions them making points of brass, copper, bone, and garfish scales, and describes how they bound them directly into reed (cane) shafts with deer sinew. James Adair describes them making points from flint, brass, deer antler, and turkey spurs. I have collected a bunch of source material over the years, there's a lot of stuff out there with very detailed descriptions of arrow and bow making written by early English, Spanish, and other explorers and traders. It's pretty interesting reading. There are very detailed descriptions of arrow-making methods, including using cane knives to cut fletching, using knives made from beaver teeth to cut nocks, making glue from hide, sinew, deer antler velvet, and fish, use of pitch and bear grease for arrow finishes, etc. Most of the Florida tribes seemed to have often used wooden foreshafts on cane arrows, as did some of the Creek tribes, and some tribes in eastern Virginia and NC. The Cherokee and Yuchi apparently pretty much never used them. When they were used, it was probably for the reasons Chris said-the foreshaft was designed to break or pull out, leaving the main shaft unharmed.