I’m not a expert with dates. Actually dates confuse me because of each country’s time zone 
I just tried to edit this formula which @ThinhDinh shared and got a good result. ( possible with js too but afraid to write because not sure if it work with device time zone 
) Maybe the legends could confirm? (not tagging because it will be a disturbance 
so naming them would be Jeff, Darren, Thinh, Robert and others)
Thinh’s post : How do I get the start date of current week? - #2 by ThinhDinh
Thinh’s formula : N-WEEKDAY(N)+2-HOUR(N)/24-MINUTE(N)/1440-SECOND(N)/86400
Edited formula by me: N - WEEKDAY(N) + 8 - HOUR(N)/24 - MINUTE(N)/1440 - SECOND(N)/86400
Result :
Thank you and have a great weekend!