If you gate check a stroller, ask about it when you are first checking in. I have seen people first mention it to the gate agent as they are boarding the plane. Doing it that way doesn't always give enough time to make sure the tag is marked correctly so it will be delivered where you want it. Sometimes the tag gives a choice of the gate or the baggage area of your final destination or at the connecting city for flights where you change planes.
Also, be sure the stroller is folded securely so that nothing will pop open while it's being loaded or unloaded. The last thing is to make sure you pick it up when you get off. Because we travel with a child who is disabled, we are usually the last off the plane. We almost always see a stroller or two sitting at the doorway waiting for people who got off before us.