The Astronomical New Moon is on Thursday 01 August 2019 at 4.12am. The crescent will not be visible in Europe on this day.
The calculations for crescent visibility on Friday 02 August 2019 for London is as follows
Crescent age. 40 hours 37 minutes
Moon lag time 1 hour 9 minutes
Crescent altitude 10 degrees
Crescent elongation 24.07 degrees
The crescent will be easily visible with naked eye.
1st Zilhajj 1440AH will be on Saturday 03 August 2019.