Perspective:
We have some unchangeable facts at our hands.
Cost reduces due to time decay. As a result each week will, almost always, show a lower low. Hence, it becomes important to know last weeks low.
Now, The real question is how much lower?
A rough analysis says, the expiry week shaves off 50 odd points. So if cost is 150 now, then rest 100 will go in subsequent three weeks. Approx 33% each week. So we can expect a lower reading of 120 ish. In the coming week. Could be a little higher by 10 points due to more volatility, which we can easily estimate by ATR on any intraday timeframe.
Now that we have a ballpark figure, our buying will be more sensible. Last purchase of 160 was kind okay too since earlier week showed 197 low. 37 points lower.
This solves one important problem. When to re-enter after stop hit? So have the answer, near the estimated low...
So, each day we have to record new cost of the pair. This will be an important tool. The above is a rough estimate. After hands on experience entries and exits are bound to improve.