RE: ". . . stay away from the open for anywhere to a half hour to an hour to let the program sellers get out and let the stock patterns start to evolve."
Every so often this statement pops up again. From a scalper's perspective, it's BS. If you want to trade the open, learn how to trade the open.
RE: "Don't trade "pre markets" (of course)...."
I disagree. If you want to trade pre-market, learn how to trade pre-market.
tttinvest, in addition to what you've already heard, you'll also eventually read somewhere that you shouldn't trade the mid-day dead zone, and then shouldn't trade in post-market, and probably some other times too. The thing is, each time of day has different characteristics, event influences, and risks. Whoever wrote "don't do it" evidently found the risk or challenge too much to bear. All times are traded very profitably, you just need to put the time in to develop the understanding and strategies necessary to deal with the challenges presented during different times of day.
RE: What is the correlation between before hours trading and the open?
If you mean predictable follow-through from premarket to regular session, really, anything can and does happen. The variables are infinite. If you put the time into it, you will find correlations and repeating behaviors, but there's no sure thing that I've found. At your stage, I think you're better served learning to react rather than trying to predict.
RE: Is anyone that is willing to trade in before hours taking a risk that their stock will be slammed by the program sellers/buyers?
Maybe someone familiar with institutional program trading can answer this as to how much actually goes on in premarket. I don't know. I've seen a few weird things that might have been attributed to that (or some guy's elbow on the button), but it's really not a factor as I see it. Compared to the slamming you can get from news in premarket, program trading is a total non-issue.
Really, from a scalper's perspective, program trading is a non-issue at any time of day. When price reverses, you reverse. If they're running it up or down, take advantage of it. If your stop is hit, get out.