Leap year starting on Monday
A leap year starting on Monday is any year with 366 days (i.e. it includes 29 February) that begins on Monday, 1 January, and ends on Tuesday, 31 December. Its dominical letters hence are GF, such as the years 1912, 1940, 1968, 1996, 2024, 2052, 2080, and 2120 in the Gregorian calendar or, likewise, 2008, 2036, and 2064 in the obsolete Julian calendar. 
Any leap year that starts on Monday, Wednesday or Thursday has two Friday the 13ths. This leap year contains two Friday the 13ths in September and December. Common years starting on Tuesday share this characteristic.
Coptic calendar
Every fourth Coptic year is a leap year "without exception", as in the Julian calendar, so the above-mentioned new year dates apply only between 1900 and 2099 inclusive in the Gregorian Calendar. In the Julian Calendar, the new year is "always" 29 August, except before a Julian leap year when it is 30 August. Easter is reckoned by the Julian Calendar in the Old Calendarist way.