I have a set up for live shows using Ableton and Reason. I typically open the Ableton file, wait until it loads and then open Reason. The reason for this is because Reason acts as a slave to Ableton, so Ableton must finish loading before Reason starts.
I tried this (with single and double ampersands), but it wants to open both of them at the same time.
open "~/first_file.als" & open "~/second_file.rns"
If this can be done with AppleScript instead, I'd be willing to do that. I'm using Alfred to run the command.