To be safe, you should wait until the end of the initial healing period, which is probably several weeks. I think you already know this.
Anytime you touch, change, or mess with a fresh piercing you run the risk of trauma to it or infection. Acrylic can't be sterilized, so you would be putting messing around putting unclean jewelry on a fresh wound. Your anatomy can be a factor, too--i.e., do the balls touch the face or sit flush against the flesh tunnel.
If your job situation means you must take these risks, so be it, but it's not ideal for healing your piercing.
ETA: The Piercing Bible says bridges take 4 to 6 months or longer for full healing. I've never had an erl (or a duke, or a . . .) but this seems to indicate it's one of the slower healing piercings, so I'd minimize jewelry changes as much as possible during this period. Maybe you can find some dental acrylic hide'em balls that would fit your barbell that could be sterlized.