Please, just put it all in with the message: "Hi. I have a quick question if you're available. Let me describe it as best I can here to start: ..."
This way even if I was not available to respond immediately, at least I have some actionable information when I do reply.
I worked for a company on the other side of the world and they'd often message me "hey, you around?" at like 5am in the morning my time. I'd get up later by that time many of them had gone home, meaning i'd have to wait for tomorrow to find out what they wanted. Which, as well as well as having to wait every interaction, also left the issue hanging over my head, fuelling anxieties.