Limit on simultaneous scheduled messages?

Just a quick question, I have a group where for funises I want to send every member (70~) a scheduled message at the same time.

Is there any sort of limit I'll run in to? I'm expecting some sort of anti-spam function to kick in and it'd ruin the surprise a bit if some messages were blocked or delayed. I am the creator/admin of the group, if that makes a difference at all.