When we flew with various American airlines, we had to ask at the counter and hope we beat out the other families to them. I have heard airlines in other countries are a bit better about reserving them beforehand if you call. I will say that by the time our daughter was 9 months, those bassinets were completely useless! They were laughably tiny and we ended up just holding her while she slept. Oh, and we usually travel with a car seat and ask at the counter and/or gate if there is an extra seat available for us to use (when we choose our seats, we always leave a seat in between ours as single travelers won't choose a middle seat unless they have to!). We've had pretty good luck with this and can then bring the car seat on board to use in the seat--I cannot tell you how much better our daughter slept in the car seat than in our arms when she got older! If the seat isn't available, we just gate check the car seat (which I would never do with our nice, expensive car seat...we have a cheap car seat designated just for air travel). Anyways, so that is an option to consider in case you don't get the bassinet.