Always assuming you have done your due diligence concerning the quality issues, look to see if the hypothetical total return is sufficient to warrant adding the stock to your portfolio. If the stock appears to be capable of doubling its value in five years, it's probably a good buy.
If you have been cautious enough in your estimates of earnings growth and future PEs, and if the potential reward is at least 3x the risk of loss, you'll have no qualms about buying the stock.
Use Your Common Sense
Investing is far from a precise science.
What you lose in accuracy because you are building one estimate upon another, you gain by being conservative in your estimates.
If you are careful to take the more cautious choice at every opportunity, you are rarely going to be disappointed at the outcome.
A small difference - a 1% difference in the risk would translate into only a small difference in the share price - is not enough to warrant waiting for the price to be just right.
If the price is more than just a little too high for the value parameters to satisfy you, however, you'll want to complete your study and wait for the price to come down to a more reasonable figure.
1. Always the Quality criteria must be met first
2. Then look at the Total Return - this must be >15% per year.
3. Only buy when the Risk is acceptable, that is, the potential reward must be at least 3x the risk of loss.
4. Don't squabble over pennies when you are buying.
REMEMBER: Prices can fluctuate by as much as 50% on either side of their averages during the course of the year; so you might be pleasantly surprised when a price you thought beyond hope just happens to materialize one day.