@SlackHQ super excited about reacji to speed up our interactions. Schedule-able slacks would make our life complete. For those of us that work across timezones and with hourly employees who are not supposed to check slack outside clocked-in hours, it would be a game changer. 
Hey there! So glad to hear that reacjis are helping with your interactions. 
Having the ability to schedule messages would be a great feature add on, we'd be happy to share this idea with the team as a future feature request. Thanks for sharing!