It's also strange that this is written as if there's no option other than "have a meeting" or "save it until tomorrow." That's what Slack is for! Start a thread, notify the right folks, but also ensure you share context about time urgency e.g. "I'd like to respond to $stakeholder today" or "Can you share thoughts sometime before standup tomorrow?" - and importantly, especially for engineers who might take things literally, make sure you share whether or not any coding action (EDIT: including digging into existing code) is requested as part of that effort.

Engineers also appreciate that their opinions are valued. Be a buffer so they don't feel like they're getting the full force of the stakeholder, but package the requests in realtime, and build a rapport so that you'll know if you're over-asking!