Question : Have you considered flying out of an airport besides Rotterdam The Hague Airport (RTM)?
Answer : Rotterdam The Hague Airport is a great airport, but in getting you to Kigali, there is a lower cost option – Amsterdam Airport Schiphol. It's just 29 miles away and flights are being booked 70% cheaper over the next two months.
Question : How long do most people visit Kigali?
Answer : Of course you're not most people, but if you were, you'd stay roughly four days.