Intervals are left-closed right-open and based on calendar days in the Vatican time zone, e.g. if he is takes office on 1 July 2026 (regardless of the time of the day) and dies or resigns on 1 July 2036 (regardless of the time of the day) then it resolves "Between 10 and 30 years" not "Between 3 and 10 years".
So far, 9 popes reigned for less than 1 month and only 2 reigned for more than 30 years, see https://en.wikipedia.org/wiki/Pope#Lengths_of_papal_reign (but note that that list uses a definition of length which is off by one day with respect to mine).
The deadline will be extended in case Pope Francis is still reigning on 31 December 2069.
Note: the pope take office immediately after being elected if he's already a bishop, but needs to be consecrated first otherwise -- but the latter has never happened since 1831.