The Astronomical New Moon is on Monday 14 December 2020 at 4.17pm. The crescent is not visible on this day.
The calculations for crescent visibility on Tuesday 15 December for London is as follows:
Sunset: 3.54 pm
Crescent age: 23 hours 37 minutes
Moon lag time: 41 minutes
Crescent altitude: 4.06 degrees
Crescent elongation: 13.21 degrees
Since the crescent can only be seen with optical aid, Wednesday 16th December 2020 will be the 30th Rabiul Akher 1442AH.
1st Jamadi ul Awwal 1442AH will Inshallah be on Thursday 17th December 2020 in Europe.