My tip is for scheduling an email in a smart campaign, I only use the "Run Later" feature even if it's just 20 minutes from now. The reason being, I ALWAYS want to double check my smart campaign once scheduled, in case of that OH SH!T moment that we've all experienced. Many years of experience trial and error have led to this smart campaign for emails routine. Basically, sending emails is a big enough deal that there's always a reason to double check what you've scheduled