When is a signal safe to act upon and what conditions should one place in these types of situations to stop oneself from jumping into every early buy signal?
What a question. It really does depend on your time frame.
For me personnally (if I was following SCR), I would either buy on the break of the trendline on Friday, or be looking to enter in first thing Monday morning.
Either way I would set a tight trailing stop-loss and keep moving it up to protect profits, and be looking to sell out at 140 (most recent resistance).
If I was looking at SCR on a longer time frame, then I would be looking to buy, (now that the resistance has gone) with a stop-loss under the rising bull trend. On this basis I would be looking for a price target of 175, although this would take several month's to come through.
As I say, it really depends on your time-frame.