If your historical forex rates are from London time zone, just use this entry point:
[Opening point of the position]
Price Move
Enter long after an upward move
Base price - Open
Price move - 50
Use previous bar value - No
That is in case if you want to open long at Open Price + 50 pips or short at Open Price - 50 pips.
If you want to open long at Open Price - 50 pips, use:
[Opening point of the position]
Price Move
Enter long after a downward move
Base price - Open
Price move - 50
Use previous bar value - No
That is because Day Opening is at 00 hrs London Time.
If your data are from different time zone you have to add additional entry time filter:
Let say you are 5hrs western than London. So your local time will be 5 o'clock when London opens.
To be able to filter the entry time you have to use 1hour chart.
[Opening point of the position]
Price Move
Enter long after an upward move
Base price - Open
Price move - 50
Use previous bar value - No
[Opening logic condition]
Entry Time
Enter the market between the specified hours
From hour (incl.) - 5
From min (incl.) - 0
Until hour (excl.) - 6
Until min( excl.) - 0
[Opening logic condition]
Enter Once
Enter no more than once a bar
Notice that I use 5 o?clock and 6 o?clock and ?Enter once a bar?. This means you will open long/short if there is upward or downward 50 pips market move during the first hour after London market opening.
Other option is to use 4 hour chart and to set ?Entry time? from 4 to 8 o?clock. But this is not exactly the London opening.
Despite the fact you can play with different time zones data and ?Entry time? filter, the best solution is to load market data from the London time zone. Of course you can continue using ?Entry Time? to specify a time horizon for the market entry.