With Ethiopian Airlines from Stockholm to Nosy Be and Moroni under 1200€, it's always 1 and 2 stops for in and outbound depending on the the destinations.
I don't know until when you have to book as I can't see it in the fare rules.
Category 6: Minimum stay requirements
TRAVEL FROM LAST STOPOVER MUST COMMENCE NO EARLIER THAN 7 DAYS AFTER DEPARTURE FROM FARE ORIGIN.Category 7: Maximum stay requirements
TRAVEL FROM LAST STOPOVER MUST COMMENCE NO LATER THAN 1 MONTH AFTER DEPARTURE FROM FARE ORIGIN.Category 8: Stopover restrictions
UNLIMITED STOPOVERS PERMITTED IN EACH DIRECTION IN ADD/LFW AT USD 70.00 EACH. INFANT IS FREE. NO STOPOVER OCCURS IF PASSENGER TAKES NEXT AVAILABLE FLIGHT WITHIN 24 HOURS. OR - UNLIMITED STOPOVERS PERMITTED IN EACH DIRECTION IN FRA/MAD/DUB/VIE/LON/ROM/STO/MIL/OSL/STO/BRU/PAR. NO STOPOVER OCCURS IF PASSENGER TAKES NEXT AVAILABLE FLIGHT WITHIN 48 HOURS. NOTE - HIP APPLIES