I'm always baffled when people say that. I'd suggest learning it even if you're still on reserve and it doesn't matter much. Start messing around with things now. This is your life you're bidding on. One mistake can cause you a whole month worth of hurt when you get close to the targeted lines. Also people senior will sometimes bid reserve. Even if you're way outside of targeted lineholders it's beneficial to try to bid a line. I've seen the most junior guy in base get a full line once because the base was understaffed and senior people bid all of the reserve lines.

The FA I was just flying with had no idea how to use PBS and ended up with a reserve line as a commuter even though she was within targeted line holders. People junior to her got lines. She was angry and asked me to look at her bid and it took me 2 seconds to figure out why she got reserve. Had she known even a slight bit about how to bid she would have had a full line with more days off and more pay.